The Florida Keys' Real 'Neighborhoods': Lower, Middle, and Upper Keys, Mile by Mile

Why 'Neighborhoods' Means Something Different on a 113-Mile Chain

Inside a single town, "neighborhoods" means named districts like Key West's Old Town or Bahama Village — walkable areas with their own character, covered in depth on that town's own page. At the regional-hub level, the equivalent buyer question isn't "which block" — it's "which stretch of the chain, and under which government." Monroe County runs the entire Keys as five separate incorporated municipalities — Key West, Marathon (incorporated 1999), Islamorada (incorporated 1997), Key Colony Beach, and Layton — plus a long list of large, populous unincorporated areas governed directly by the county, including Key Largo, Big Pine Key, Stock Island, Duck Key, Cudjoe Key, Sugarloaf Key, Summerland Key, and Ramrod Key. That patchwork, not a map of subdivisions, is the real starting geography here.

This page groups those communities using the informal, widely-used Lower/Middle/Upper Keys breakdown that shows up across Keys real-estate and travel guides — it is a general, commonly understood way locals and brokers talk about the chain, not an officially platted boundary line, and this research did not turn up a single authoritative source drawing exact mile-marker cutoffs between the three sections. Treat the groupings below as orientation, not survey-grade boundaries.

The Mile-Marker System: Your Real "Address" for Narrowing In

Before comparing neighborhoods or towns, learn the mile-marker system — it's how real estate listings, marinas, and restaurants across the entire chain actually locate themselves, since many Keys properties were never assigned conventional numbered street addresses. The Overseas Highway (US-1/State Road 5) runs on green mile-marker signs from MM 0 in Key West to roughly MM 126 near Florida City on the mainland, covering the chain's roughly 113 miles. A listing described as "MM 82, Oceanside" is telling you both which side of the highway a property sits on (oceanside faces the Atlantic; bayside/gulfside faces Florida Bay or the Gulf) and, once you know the general MM ranges below, roughly which section of the chain you're looking at.

Two specific MM references are confirmed for communities already built out on this site: Key West sits at MM 0, the southern end of the chain, and Islamorada spans roughly MM 72-90. Beyond those two, this page does not state precise mile-marker boundaries for Marathon, Key Largo, or the other communities below, because that level of exact detail wasn't confirmed in the research behind this page — each community's own dedicated page will carry its specific MM range once it's built.

Lower Keys: Key West Through the Backcountry

The Lower Keys run from Key West, at the southern end of the chain, up through the string of smaller keys before the Marathon area. Key West itself is the chain's largest incorporated city and its only entry with its own dedicated, deeply-researched page on this site today, covering its real internal neighborhoods (Old Town, Bahama Village, Truman Annex, the Meadows, New Town) in depth. Stock Island, immediately next door to Key West and connected by a short bridge, is a separate, unincorporated, working-waterfront community rather than part of the City of Key West — a distinction Key West's own neighborhoods page covers in more detail, worth knowing since it's easy to assume the two are the same place.

Further up the chain, Big Pine Key, Cudjoe Key, Sugarloaf Key, Summerland Key, and Ramrod Key are all large, populous, unincorporated communities governed directly by Monroe County rather than any city hall. Big Pine Key and neighboring No Name Key are also the specific home of the National Key Deer Refuge, a federal refuge protecting the Key deer — a diminutive white-tailed deer subspecies found nowhere else on Earth — and Monroe County maintains its own Key Deer Habitat Conservation Plan just for that area, a genuinely Lower-Keys-specific environmental fact that shapes what can be built there.

Middle Keys: Marathon and Its Neighbors

The Middle Keys center on Marathon, the chain's second incorporated municipality, which became its own city in 1999. Marathon does not yet have its own dedicated page on this site, though it's slated to get one, following the same pattern as Key West and Islamorada. Key Colony Beach, one of the five incorporated municipalities named in this research, is a separately-governed small island community near Marathon; this page does not have a confirmed, sourced mile-marker range for it and isn't going to guess one. Duck Key, a named unincorporated community in the same general area, follows the same pattern — real, and part of the chain's unincorporated patchwork, without a precise boundary confirmed here.

Layton, the fifth incorporated municipality named in Monroe County's own municipalities list, is genuinely small, and this research did not confirm enough sourced detail about its specific location within the Lower/Middle/Upper framework to place it confidently on this page. That's an honest gap rather than a filled-in guess — confirm Layton's specifics directly with Monroe County or a local agent if it's relevant to your search.

Upper Keys: Islamorada and Key Largo, Closest to the Mainland

The Upper Keys are the stretch closest to the Florida mainland, running from around Islamorada up through Key Largo toward Florida City at the top of the chain. Islamorada, incorporated in 1997 from six historic communities merged into one village government, spans roughly MM 72-90 and carries the "Sport Fishing Capital of the World" identity — it also recorded the highest single death toll of the 1935 Labor Day Hurricane, the storm that ended the Overseas Railroad and led to the highway that replaced it. Islamorada's own dedicated page, covering its community-level detail, is in progress on this site as of this writing.

Key Largo, at the chain's northern end nearest the mainland, is the largest unincorporated community in the Keys and does not yet have its own dedicated page here, though — like Marathon — it's expected to get one as this site's Keys coverage builds out. For now, treat "Key Largo" as a name to watch for rather than a place this page can describe neighborhood by neighborhood.

Incorporated vs. Unincorporated: Why the Distinction Actually Matters

Whether a given address sits inside one of the five incorporated municipalities or in unincorporated Monroe County affects real, practical things for a buyer: zoning, permitting, and local ordinances are set by that municipality's own government if it's incorporated, or by the county directly if it isn't — and those rules can genuinely differ from one causeway-connected key to the next along the same highway, even though the drive between them takes minutes. The growth-control framework layered on top of that patchwork is chain-wide either way: the Rate of Growth Ordinance (ROGO) for residential construction and its non-residential counterpart (NROGO) operate under Monroe County's Land Development Code, and each incorporated municipality (Key West, Marathon, Islamorada, Key Colony Beach, and Layton) also runs its own parallel allocation system built on the same state-mandated logic, tied to the Florida Keys' designation as a state "Area of Critical State Concern" and its 24-hour hurricane-evacuation-clearance standard.

In practice, that means a buyer can't assume "the Keys" has one zoning code, one permitting office, or one set of short-term-rental rules — confirm which government actually has jurisdiction over a specific property (the relevant incorporated municipality, or Monroe County directly) before assuming anything about what you can build, rent, or renovate there.

What This Page Doesn't Cover Yet, and Where to Get It

This page is a chain-wide orientation, not a community-by-community deep dive. Key West's own dedicated neighborhoods page already covers its real internal geography — Old Town, Bahama Village, Truman Annex, the Meadows, New Town, and its relationship to next-door Stock Island — in far more depth than a regional hub page should attempt. Islamorada's own community-level page is in progress. Marathon, Key Largo, Big Pine Key, and the rest of the chain's communities named on this page don't have their own dedicated pages yet, but are expected to get them over time, the same way this site has built out Cape Cod and the Outer Banks one town at a time.

If you need community-specific detail today — a specific stretch of Key Largo, a particular part of Marathon, or exactly which mile marker a listing sits on — a local buyer's agent who works that specific part of the chain day-to-day is the right resource right now, not a placeholder estimate on this page.

A Professional-Consult Disclaimer

Municipal boundaries, incorporation status, zoning, and any HOA or deed restrictions can vary community to community and even block to block across the Keys, and the Lower/Middle/Upper groupings on this page are informal orientation, not a survey-grade or legally defined boundary system. Confirm current jurisdiction, zoning, and any restrictions directly with Monroe County, the relevant incorporated municipality, or a Florida-licensed real estate agent before making any purchase decision. Nothing on this page is legal, real estate, tax, or insurance advice.