Understanding Carrying Capacity - What Every St. Simons Island Resident Should Know About Growth, Traffic, and Planning.
Written by: Michael Collett | July 2026.
Purpose of this paper. This paper does not advocate for incorporation, county government, or any particular political outcome. Its purpose is to provide a common factual foundation for future community discussions about growth, traffic, and long-term planning.
This paper explores:
• How close is St. Simons to its road capacity today, and where does the pressure actually show up?
• How does St. Simons compare to Hilton Head — the community we've long said we don't want to become — on the numbers that actually matter?
• How did we get here, and what has county governance done (and not done) about it over the last decade?
• What development is already coming regardless of any policy decision, and how much more could existing zoning still allow?
• What choices are actually on the table now, while there's still time to act on them?
Whether you've been on the island for decades or you just made it your home — full-time or part-time — chances are you've felt it: getting around St. Simons has gotten harder. This document lays out the specifics: how our traffic situation actually works, how we got here, and what's worth weighing — both by the county leadership who set the rules and the advocates working to protect the roads we depend on.
Every road system has a limit to how much traffic it can carry. Barrier islands simply reach it sooner, because geography caps how much their roads can expand. On St. Simons, that limit is visible on any map: one causeway to the mainland, a small network of island roads, marsh on one side and homes on the other. St. Simons has roughly 11,000 occupied homes today. The question isn't whether the island has a carrying capacity. The question is how much growth can be absorbed—and whether anyone is measuring how much capacity remains.
There are standard ways to measure this: how much a road can handle, and how much traffic new development adds. Compare the two, and you know whether the roads can keep up. Using those standard trip-generation estimates, our roughly 11,000 occupied housing units generate tens of thousands of vehicle trips every day — all flowing through the same causeway and a handful of key island corridors that cannot meaningfully be widened.
Here's where that pressure actually shows up. Fortunately, our causeway still has room — running at roughly half capacity off-season and just over three-fifths once summer traffic and north-end buildout are factored in. The real pressure point is Frederica Road at Sea Island Road, the island's most congested intersection: it's already estimated to run at about 105% of practical capacity during summer peak periods
— over capacity before the roughly 200 additional north-end homes now under construction even arrive. And capacity math is unforgiving near the limit: delay isn't linear. As an intersection approaches its practical capacity, each added vehicle multiplies everyone's wait. That's why a modest summer increase
(20–30% more people as seasonal homes fill) doesn't feel merely 25% worse; the seasonal increase often tips intersections that were already operating near capacity into sustained backups. Summer isn't the exception on a resort island. It's our regular stress test.
Something changed in the last ten years that made every one of those numbers move faster. St. Simons caught the leading edge of three national currents at once: the largest generational wealth transfer in American history reaching retirement age, the pandemic-era migration of affluent households to coastal and small-town settings, and a broader movement of people relocating in search of communities that fit their preferences. The island's numbers show the result. Median household income rose from roughly $87,000 to over $106,000 in recent years. Home values roughly doubled over the past decade, with median sale prices now in the $700,000–$775,000 range and average sales (driven by higher-end properties) reported around $1.35 million in some periods. Million-dollar homes, once rare, now represent a much larger share of transactions. Cash buyers have remained active even amid higher interest rates, and the share of homes held for seasonal or occasional use has remained substantial.
High-end homes and affluent buyers matter for traffic in a way that's easy to miss. Affluent households don't just generate their own trips — they generate employment. Every high-end home means lawn crews, pool service, housecleaning, contractors, and deliveries; every short-term rental adds turnover cleanings all summer at exactly the peak. And because many island jobs are low-wage relative to the cost of living, most of that workforce can't afford to live on the island and instead commutes from the mainland every day. Prosperity, in other words, generates traffic twice: once through the people who arrive, and again through the people employed to serve them. That is not a criticism of anyone who moved here — most came for the same qualities long-time residents cherish. It's simply how traffic keeps growing even when the year-round population barely moves.
Why look 60 miles north for a comparison at all? Because you've probably said it yourself, or heard a neighbor say it: "We don't want to become Hilton Head." That instinct is right. And it's exactly why the comparison is worth making carefully, instead of waving it off.
Hilton Head isn't a hypothetical warning. It's the same kind of barrier island, just decades further down the same road — so we can actually see how the story ends. Their big wave of growth hit in the 1960s and '70s, while the county still ran things and before their town even existed. By the time they incorporated in 1983, that density was already locked in.
St. Simons is only now entering that same stretch of the curve. The wealth transfer and migration wave driving our growth has unfolded over the last ten years — not the last fifty, the way Hilton Head's did. That difference in timing is exactly why this comparison is useful instead of alarmist. Hilton Head isn't a rival, and it isn't our fate. Think of it more like a finished experiment, run under very similar starting conditions. The results are already in. That means we get to learn from them, instead of repeating them blind.
We know that mechanism is real, because it already played out there — and the numbers say we're closer to it than most people realize. Dividing each island's housing units by its own land area gives a like-for-like density figure, independent of seasonal population swings: St. Simons already sits within roughly 2–4% of Hilton Head's housing density (676 units per square mile here versus 689–702 there, depending on which published Hilton Head land-area figure is used). By population density, St. Simons is actually slightly higher (942 versus 895 people per square mile), since more of our housing is occupied year-round rather than seasonally. We're not on a path toward becoming Hilton Head — by this measure, we're already there. The difference that remains is mostly scale: Hilton Head has about 2.7 times as many homes, and its mainland gateway corridor is estimated to already run 25–125% over planning capacity depending on the season. A 2021 estimate to replace just one span of their bridge ran $78 million — a dated figure, and a fraction of the cost of a full corridor fix. To be fair, their island road network is larger than ours — they even built a second cross-island parkway, an $83 million relief route we have no room to duplicate. Yet congestion remained a significant issue despite those major roadway investments, because the root cause was never road supply. It was total economic intensity — every home, hotel room, and restaurant generating trips from residents, visitors, and the workers who drive in to serve them — committed in the 1960s and '70s, before their town even existed, without anyone totaling the ledger.
Which brings us to an honest look in the mirror: we've held onto that instinct — "we don't want to become Hilton Head" — for decades, while already arriving at a comparable density. We also spent those decades questioning whether their incorporation accomplished anything. Supporters of Hilton Head's governance model point to a substantial record: 1,350 acres purchased, nearly five million square feet of development precluded, and one of the strictest land management codes in the Southeast — not a cure for congestion, but by their account a materially better island than the alternative. Meanwhile, St. Simons examined self-government in the 1990s, commissioned a feasibility study in 2015, and watched township legislation stall in 2016 — each effort ending not in a decision against, but in no decision at all. "Do nothing" was never chosen deliberately. It has nonetheless shaped today's realities: zoning written at the county level, density decided off-island, and the traffic we experience.
This spring brought the first real change to that pattern in years. Glynn County adopted a comprehensive rewrite of its zoning code — Envision Glynn — unanimously on April 16, 2026, effective July 1, 2026, updating density standards, tree canopy protection, and accessory dwelling unit rules for the first time since the code's last major overhaul. That's a real step, and it deserves to be recognized as one. It's also worth being clear-eyed about what it does and doesn't resolve. The rewrite sets new rules for how individual parcels may be developed; it does not establish a mechanism for testing whether the cumulative effect of those parcels, added together, still fits within what our roads can carry. And the county's own process this spring illustrated the point directly: on the rewrite's data center provisions, the joint Islands and Mainland Planning Commissions recommended the Board pause and strengthen the ordinance, and the Board adopted it without the pause. The Islands Planning Commission's rezoning recommendations, like that one, are advisory rather than binding — the decision still rests with the full Board of Commissioners. Whatever one thinks of that particular outcome, it's a clean illustration of where authority over island-specific growth decisions actually sits today.
Over the last decade, county leadership has devoted significant attention to roadway improvements and intersection projects. Those efforts may improve operations, but they do not by themselves answer the broader question of how much cumulative growth the island's transportation system can ultimately absorb. They have advanced specific projects, including the St. Simons Gateway improvements. The flagship of those efforts — a roundabout at Frederica and Sea Island Roads, first identified in county planning as far back as 2001 and formally approved and funded in 2022 — has not actually broken ground: the project needs roughly half an acre of the St. Simons Land Trust's protected Old Stables Corner property (plus pieces of eight other parcels), the county has indicated it may use eminent domain to acquire it, and the Land Trust has publicly objected. That land dispute is real, but it's not the only thing that's gone unresolved. A 2021 peer-review evaluation by Buckholz Traffic Engineering, commissioned to check the county's 2016 traffic study, found that the existing signalized intersection — simply retimed— was projected to operate acceptably through 2035, and that the roundabout as designed would actually perform worse than the existing signals during peak summer conditions. The review also questioned the underlying study's single islandwide growth factor and its 20-year design horizon, calling that combination prone to over-building. Whichever conclusion is right, here's the point that matters more: that technical question has sat unresolved since 2021, the same way the land dispute has sat unresolved since 2022 — because there is no standing forum where either kind of question gets revisited on a deadline. This isn't a minor scheduling delay. It's a live illustration of the deeper problem: even a fully designed, fully funded project can sit frozen for years once it collides with an unresolved land-use conflict or an unresolved engineering question, with no mechanism forcing either back to the table. A binding cumulative-capacity framework wouldn't resolve this particular dispute on its own, but it would mean these questions get revisited against total island capacity on a schedule — rather than sitting wherever they landed years ago while the island's headroom quietly shrinks in the meantime.
The two islands now differ most in one asset: headroom. Theirs is largely spent. Ours is diminishing with each approval — and on a barrier island, capacity once committed is rarely recovered.
Looking forward, the trend runs in one direction — and much of it is no longer hypothetical. Three current north-end developments alone — West Point (168 acres, with seven more phases and over 100 acres still to be built out), The Canopy (a 25-lot gated community backing onto Land Trust property), and Frederica Marsh Cottages (27 homes adjacent to Frederica Golf Club) — already account for well over 200 approved or in-progress homes, with construction visibly underway on all three. That's roughly a 2% increase on top of the island's existing 11,000 homes from these three projects alone — before counting the island's other north-end subdivisions. Replacing a single-family home with multiple residential units can substantially increase the vehicle trips generated by that parcel — and many smaller redevelopment projects may not individually trigger comprehensive traffic review, even as their effects accumulate on the same corridors. Roundabouts and signal improvements are worthwhile, but they cannot be effective without looking at the big picture.
It's worth being clear about what that 200-home figure really means, because on its own it makes the situation look smaller than it is. That number only counts homes already approved and under construction on three parcels. It's a floor, not a ceiling.
A separate look at the island's remaining vacant, zoned land (full breakdown in the appendix) suggests the island could realistically end up with somewhere between 1,700 and 5,200 more homes — and that's before counting the newly allowed accessory dwelling units. Set against that range, the 200 homes now under construction are less than 10% of what our current zoning could ultimately allow.
This matters for what's actually achievable, not just what's desirable. Under Georgia law, an approved subdivision plat generally carries a vested right to build it out — no future zoning change, and no change in how the island is governed, undoes an entitlement that's already been granted. That means the 200-plus homes already in West Point's remaining phases, The Canopy, and Frederica Marsh Cottages are coming regardless of what happens next — and, as noted above, that figure is only a small down payment on the island's much larger remaining buildout potential. Parcel-level county data puts the island's total remaining vacant land at 948 parcels covering roughly 3,212 acres. Of that, about 1,922 acres across 228 parcels sit in Planned Development zoning (PD, PDG, and PDR) — much of which may already carry vested density from prior rezonings, placing it closer to "coming regardless" than to land still open for protection. Separately, five of the island's established neighborhoods hold roughly 1,312 already-platted, permit-ready "lots of record" — vacant lots that typically need no further zoning approval at all. The practical question isn't whether to stop what's already approved; it's where to focus finite attention and finite dollars given that reality. Two things follow. First, hold the line against additional high-density rezonings in areas that are already built out, rather than layering new density on top of corridors already near capacity. Second, treat the island's remaining unentitled acreage — land outside these already-zoned PD tracts and platted lots — as the highest-leverage target for conservation, since that is the land where preservation can still happen before, rather than after, the fact. Every acre moved into protected status before it reaches the county's approval process is traffic permanently prevented; every acre that gets platted first is a home that vested rights will protect regardless of any later governance change. A parcel-level breakdown of the island's vacant land by zoning designation appears in the table at the end of this letter.
Regardless of where residents stand on incorporation, county reform, or maintaining the current structure, there are practical tools worth considering. Many could be implemented by Glynn County under existing authority, others through state legislation, and some through a future local government should residents ever choose that path. The purpose here is to identify proven planning tools—not to prescribe one form of government.
Ideas drawn from other barrier islands include:
• A full buildout traffic analysis under the new zoning code, so the total ledger under Envision Glynn's updated density rules is finally visible, not just parcel by parcel.
• Cumulative corridor review, so smaller projects are measured against the combined load on a corridor, not just their own trip generation.
• An Adequate Public Facilities Ordinance, requiring new development to demonstrate available road capacity — using the same Highway Capacity Manual and ITE Trip Generation methodology already applied here — before approval, not after.
• Binding, rather than advisory, authority for the Islands Planning Commission over rezoning decisions — the same binding authority it already exercises over plat review — so growth decisions made closest to the resource aren't routinely finalized somewhere else.
• Development impact fees, which Georgia law permits and which would have growth fund the intersection improvements it necessitates, potentially paired with a Community Improvement District so commercial and rental properties can fund infrastructure directly.
• A free, seasonal beach shuttle from off-island parking — modeled on Acadia National Park's "Island Explorer," which offloads tens of thousands of visitor vehicles a summer on a similarly constrained island by giving beachgoers an alternative to driving straight to the coast.
• Prioritized conservation of the island's remaining unentitled acreage, since that land — not what's already platted — is the only place where preservation can still happen before development rights vest.
• Protection of the island's remaining modest housing, which keeps workers closer to their jobs and off the causeway.
Absent deliberate action, the next five to ten years are fairly predictable. The 200-plus homes already approved on the north end will be built regardless of any policy change, adding their trips to Frederica and Sea Island Roads whether or not anything else happens — and that's before the island's much larger remaining buildout potential, discussed above, is factored in at all. Gateway and intersection projects now in planning or early construction may provide temporary relief, but traffic studies (GWES Gateway) projecting to 2040–2045 already show worsening Level of Service ratings and longer peak delays — even under conservative growth assumptions. What begins as seasonal backups will increasingly spill into shoulder seasons and shoulder hours, eroding response times for emergency services, frustrating daily commutes, and pressuring the island's remaining workforce housing. The island's appeal as a livable community will quietly diminish, even as its popularity as a destination grows — mirroring the pattern seen elsewhere when cumulative intensity outpaces infrastructure and planning.
Envision Glynn changed the rules for individual parcels. It has not yet answered the harder question: what the island can carry in total, and who checks that math before the next approval.
The benefits of addressing this now, rather than later, don't accrue to one side of any debate — nearly everyone on the island has a stake in getting it right. Current homeowners keep the quiet, walkable character that drew most of us here, and the property values that depend on that character holding up over time. Visitors and the businesses built around them keep an island that's still pleasant to spend a week on, rather than one where the drive to dinner becomes the story of the trip. Employees who commute onto the island every day benefit from housing that stays within reach of the causeway rather than being pushed further onto the mainland with every year that passes. And in a hurricane evacuation, every intersection operating below capacity today is measured in minutes saved getting roughly 11,000 households off the island quickly and safely — on a barrier island, traffic capacity is not only a quality-of-life question, but also a safety margin. Addressing it now costs far less, in every sense, than addressing it after the headroom is gone.
Regardless of where residents stand on incorporation, county reform, or maintaining the current structure, one question deserves broad agreement: How much additional growth can St. Simons reasonably absorb while preserving the qualities that brought people here? Examining carrying capacity deliberately is valuable regardless of which governance model residents ultimately prefer. Hilton Head's window closed before their town could act on it. By every standard measure, ours is still open.
Planned Development total (PD + PDG + PDR): 228 parcels, ~1,922 acres — the figure cited above. Separately, county records identify approximately 1,312 additional “lots of record” (already-platted, individually vacant lots requiring no further subdivision approval) across five established neighborhoods: Village Area (469), German Village (449), Glynn Haven (273), East Beach (76), and St. Simons Heights (45).
A note on sources: figures in this letter draw from U.S. Census data, the Highway Capacity Manual, the ITE Trip Generation Manual, Glynn County parcel and zoning data, and county and state planning documents. Some corridor- and intersection-level capacity estimates are planning-level and illustrative rather than the product of a full traffic engineering study, and are labeled as such where used. This is intended as a basis for public discussion, not a substitute for a formal county traffic analysis.
What the Comparison Shows
Hilton Head demonstrates that congestion on a barrier island develops gradually and then accelerates as key intersections and gateway corridors approach their practical limits. Significant roadway investments improved operations but did not fully offset the cumulative effects of decades of development. St. Simons remains in a different position. Portions of its transportation system still retain available capacity, but several critical intersections already approach or exceed practical capacity during peak periods. That remaining headroom provides an opportunity to evaluate future growth before it is fully committed.
The comparison is not intended to suggest that St. Simons will become Hilton Head. Rather, it illustrates how two barrier islands with similar physical constraints can experience similar transportation challenges as development accumulates over time.
About the Author
Michael Collett is a retired technology and business executive with more than four decades of experience leading large-scale consulting, data analytics, and strategic planning initiatives for Fortune 500 organizations. Throughout his career, he worked with public- and private-sector leaders to evaluate complex issues, assess long-term impacts, and support informed decision-making through data-driven analysis.
Like many residents, he chose St. Simons Island because of its unique natural beauty, history, and sense of community. This paper was written independently as a civic contribution to encourage thoughtful discussion about the island's future. It is not sponsored by, or written on behalf of, any political organization, advocacy group, governmental entity, or campaign.
The purpose of this paper is not to advocate for incorporation or any other specific governance model. Rather, it is to encourage residents to better understand the concept of carrying capacity, review publicly available information, ask informed questions, and participate respectfully in conversations about growth, transportation, land use, and long-term stewardship.
Mr. Collett welcomes constructive dialogue and encourages readers with differing viewpoints to examine the underlying data, challenge assumptions respectfully, and continue working together toward practical solutions that preserve the qualities that make St. Simons Island a remarkable place to live, work, and visit.
Frequently Asked Questions
Is this paper advocating for incorporation?
No. This paper is intended to explain carrying capacity, growth, traffic, and planning. It does not endorse incorporation, county government, or any other governance model. Its goal is to provide a factual foundation for informed community discussion.
Could these recommendations be implemented without incorporation?
Yes. Many of the planning tools discussed—including cumulative traffic analysis, comprehensive planning updates, conservation strategies, impact fees where authorized, and greater transparency—could be pursued through Glynn County under existing authority or through state legislation.
Does this paper recommend higher taxes?
No. The paper does not recommend increasing taxes. Any future governance proposal should clearly identify costs, revenues, and taxpayer impacts before residents are asked to make decisions.
Does this paper conclude St. Simons has exceeded its carrying capacity?
No. The paper concludes that some transportation facilities approach or exceed practical capacity during peak periods while others retain available capacity. The central question is how future growth should be managed before remaining capacity is consumed.
Is the traffic analysis a substitute for a professional engineering study?
No. The discussion relies on accepted transportation methodologies, existing studies, and publicly available planning information. It is intended to encourage additional engineering analysis—not replace one.
What is the principal question this paper asks?
Regardless of individual views on incorporation, county reform, or maintaining the current system, the paper asks: How much additional growth can St. Simons reasonably absorb while preserving the qualities that make the island special?
Additional FAQ: Sources and Research
Where did the information in this paper come from?
The information presented in this paper was developed by reviewing, comparing, and synthesizing a wide range of publicly available studies, planning documents, engineering analyses, government reports, and demographic data prepared over many years.
Rather than relying on a single report, this paper brings together findings from numerous independent sources, including:
• Glynn County planning documents and zoning ordinances
• Envision Glynn (2026) comprehensive zoning update
• Glynn County parcel, zoning, and GIS data
• St. Simons Island traffic studies and transportation analyses
• Southeastern Engineering (SEI) traffic studies, technical memoranda, and presentations
prepared for Glynn County
• Buckholz Traffic Engineering's independent peer review
• Georgia Department of Transportation planning information
• Highway Capacity Manual (Transportation Research Board)
• Institute of Transportation Engineers (ITE) Trip Generation Manual
• U.S. Census Bureau and American Community Survey
• Hilton Head Island planning and transportation studies
• Public Planning Commission and Board of Commissioners meeting records
• Georgia planning, conservation, and barrier island research
The purpose of this paper is to organize and explain information that already exists across these sources in a way that is easier for residents to understand. Looking at the studies collectively provides a more complete picture of St. Simons Island's carrying capacity, transportation system, growth patterns, and planning challenges than any single report alone. No single study tells the entire story. This paper was written to bring those studies together into one comprehensive, fact-based resource for the community. www.stsimonsinformationforum.com
-This paper was reproduced in its entirety for the benefit of our readers; we commend Michael Collett for his work and welcome more focused discussion on this topic. - Page Aiken, Aiken Partners Real Estate.