Casco Bay Islands Neighborhoods: Five Separate Islands, Each Its Own Community

Long Island: The Island That Seceded From Portland Over a Tax Bill

Long Island had 234 year-round residents at the 2020 Census (225 registered voters as of March 2025), on a town whose total area is mostly water -- 33.52 square miles on paper, but just 1.42 square miles of actual land. The main island is commonly described as roughly three miles long and about a mile wide. Summer population swells to somewhere in the range of 800 to 1,000, a several-times multiple of the year-round count.

The defining fact about Long Island as a community is that it is not part of Portland at all: it seceded from the City of Portland on July 1, 1993, becoming its own incorporated town, after Portland's 1990 property-tax revaluation sharply raised taxes on the island relative to the municipal services residents felt they were actually getting. That is a genuine, separate secession story -- distinct from, and thirteen years earlier than, Chebeague's own secession below, and distinct from Peaks Island's still-pending secession bill against Portland, which belongs to that island's own page.

Long Island's history includes WWI- and WWII-era military installations (searchlights, radar stations, naval training facilities), a destructive fire in June 1914, a failed 1969 proposal for a supertanker port that residents fought off, and a real, documented environmental low point: the 1972 oil spill from the tanker Tamano, which contaminated the island's West Beach. Casco Bay Lines' passenger service to Long Island typically runs 30 minutes to one hour depending on route and stops, with a reservation-based vehicle ferry also available.

Chebeague Island: The Largest of the Five, With Its Own School and Two Ferry Lines

Chebeague is the largest of these five islands by both population and land, with 396 year-round residents at the 2020 Census -- up 16% from 2010 -- on 3.56 square miles of land (24.56 square miles including surrounding water). Casco Bay Lines' own island page separately cites "over 360 year-round people and more than 1,600 summer residents," a close but not identical figure to the Census count; both numbers are worth knowing rather than picking one to force a reconciliation.

Chebeague seceded from the town of Cumberland, Maine, on July 1, 2007, after 184 years as part of Cumberland, through a real, citable Maine Legislature public law (PS Law, Chapter 47) following a lopsided statewide legislative vote in April 2006. Unlike Long Island's tax-revaluation grievance, Chebeague's secession was driven by a different motivator entirely: protecting the island's own small elementary school amid Cumberland-district downsizing pressure.

Chebeague is also the only island in this group served by two separate ferry operators: the Chebeague Transportation Company runs a roughly 15-minute passenger run from Cousins Island in Yarmouth to the island's Stone Wharf, plus a vehicle and freight barge by reservation, while Casco Bay Lines runs a longer, roughly 60-to-90-minute route from downtown Portland to Chandler's Cove wharf. Chebeague also has its own Great Chebeague Golf Club, a nine-hole course whose clubhouse is a repurposed circa-1807 residence listed on the National Register of Historic Places in 2015 -- a genuinely distinctive amenity none of the other four islands in this group has an equivalent of.

Great Diamond Island: A Former Army Fort Reborn as a Gated Residential Community

Great Diamond Island is part of the City of Portland -- it never had its own secession story the way Long Island or Chebeague did. Its year-round population was 77 at the 2000 Census, the most recent figure independently confirmed; a commercial demographics source (Point2Homes) shows a much smaller current snapshot of around 12 residents and 6 occupied households, which may reflect a narrower survey boundary or a different vintage than the island-wide 2000 Census count. That discrepancy is worth flagging honestly rather than resolving with a guess.

The island's defining feature is Fort McKinley, a major coastal-defense installation built roughly 1897 to 1906, eventually covering 111 acres with nine gun batteries. It housed over 1,400 enlisted personnel after a 1940-41 expansion, but by the end of 1943 most of its guns had been removed as the Army shifted its coastal-defense focus elsewhere in Casco Bay. The Navy sold the site to private interests in 1961, and the Fort McKinley Historic District was listed on the National Register of Historic Places in 1985.

Today the redeveloped fort -- former barracks and officers' quarters converted into homes -- operates as Diamond Cove, a gated, mostly private residential community. Public-facing businesses inside it include Diamond's Edge Restaurant & Marina and the Diamond Cove General Store, plus the Inn at Diamond Cove. Casco Bay Lines serves a Diamond Cove stop on the island's northeastern side.

Little Diamond Island: A Near-Empty Seasonal Retreat, Stated Honestly

Little Diamond Island is also part of the City of Portland, with no secession story of its own, and it is the thinnest community of the five by a wide margin: just 5 year-round residents at the 2000 Census, a figure explicitly attributed to the island's water supply being shut off in winter, which limits who can actually live there year-round. A more recent commercial demographics snapshot (Point2Homes, vintage not independently confirmed) shows an even smaller current figure -- as few as 2 residents and 1 occupied household out of 3 total housing units.

Little Diamond is predominantly privately owned and functions as a vacation retreat rather than a residential community in any conventional sense. There is no dining establishment of any kind confirmed on the island, and no dedicated school -- consistent with a place whose identity is its thinness rather than any amenity or civic institution. Casco Bay Lines serves the island; buyers should treat it as a genuinely different kind of purchase than a year-round home anywhere else in this group.

Cliff Island: No Paved Roads, the Longest Ferry Ride, and a Real Year-Round Civic Life

Cliff Island, part of the City of Portland, had approximately 60 year-round residents as of the 2000 Census, swelling to roughly 200 in summer. It is the farthest island Casco Bay Lines serves, with a one-way run commonly cited at roughly 60 to 120 minutes depending on route and freight stops -- the longest of the five. Five daily round trips operate year-round, with a barge ramp added in 2008 to support freight delivery.

What genuinely sets Cliff Island apart is that it is the only year-round-inhabited island in Casco Bay with entirely unpaved roads: residents get around by walking, bicycle, and golf cart rather than car. It maintains real, active civic institutions for a community its size -- a one-room schoolhouse serving pre-K through 5th grade, a 100-plus-year-old library, a summers-only Historical Society museum, and an all-volunteer "ACE" organization (athletics, conservation, education, arts and crafts, entertainment) that runs the island's event calendar.

Casco Bay Lines describes Cliff Island as "the smallest year-round inhabited island in Casco Bay," a claim that sits in some tension with Little Diamond's even-smaller population figures above. That tension is likely explained by Little Diamond functioning as a private seasonal retreat rather than an organized year-round community, while Cliff Island has a genuine, organized civic and school life -- but this page states both facts as found rather than asserting one island is definitively "smaller" than the other.

Why These Five Islands Do Not Work Like Mainland Neighborhoods

Every one of these islands shows a dramatic gap between its year-round population and its summer population -- roughly three to four times higher in season, sometimes more -- which means real estate here splits between a small, committed year-round community and a much larger seasonal-ownership base. That is a fundamentally different ownership dynamic than a mainland coastal suburb, and it plays out differently on each island: Chebeague and Cliff Island both maintain their own on-island elementary schools, with older students commuting daily by ferry to mainland Portland-area schools, while Great Diamond and Little Diamond were not found to have any dedicated on-island school at all.

Every one of these islands also depends on Casco Bay Lines (and, for Chebeague, also the Chebeague Transportation Company) for groceries, mail, medical trips, and building materials -- a structurally different daily-living reality than any bridge-connected market on this site, and one that compounds storm and emergency-response risk in a way a road-connected coastal town does not face.

A Live 2026 Story Affecting Every Island in This Group

The single biggest current story touching all five islands at once is a 2026 Casco Bay Lines fare dispute. The carrier proposed raising peak-season round-trip adult passenger fares from $14 to $17 -- a 21% increase, the second passenger fare hike in three years -- citing rising fuel, labor, maintenance, insurance, and regulatory costs. Hundreds of island residents filed a formal petition over affordability and notice concerns, and on June 16, 2026, the Maine Public Utilities Commission unanimously voted to open a full, formal investigation into both the financial justification for the increases and the rate-setting process itself. As of that vote, the new fares remained in effect for the summer season while the investigation proceeded.

Separately, Casco Bay Lines' own current rates page lists a peak-season (April 18-October 12, 2026) round-trip adult fare of $16.00 and an off-peak-season round-trip adult fare of $8.00, applied as flat rates across all seven stops the line serves -- Peaks, Little Diamond, Great Diamond, Diamond Cove, Long, Chebeague, and Cliff -- regardless of distance, meaning the roughly two-hour round trip to Cliff Island costs the same as the short hop to Peaks Island. That $16 figure does not exactly match the $17 figure discussed in the April 2026 proposal coverage; this likely reflects the gap between a proposed number and an adopted one, and either figure should be re-verified directly with the carrier before being treated as final.

A second, longer-running story is a real island housing shortage: a July 2025 Portland Press Herald investigation on Maine's unbridged islands -- naming Chebeague, Long Island, and Cliff Island among Casco Bay islands examined -- found a median island resident age of 56 versus 44 statewide, construction costs roughly 30% higher than the mainland due to barge transport, and housing increasingly converted from year-round to seasonal use by outside buyers. Chebeague's own community association has run real, named affordable-housing projects for over a decade, including modular duplexes built with MaineHousing grants.

What This Means If You Are Comparing These Five Islands

There is no single "Casco Bay islands" real estate market to evaluate -- there are five separate, thin, ferry-access-limited micro-markets, and each should be judged on its own terms rather than as an undifferentiated group. Chebeague's Zillow-tracked typical home value sits at $666,975 (down 1.8% over the past year, as of data through June 30, 2026), and Long Island's sits at $609,323 (down 4.2% over the past year, as of data through January 31, 2026). A specific, current typical-value figure for Great Diamond Island could not be independently confirmed this pass despite Zillow maintaining dedicated listing pages for it, and no reliable median-sale or typical-value figure exists for Little Diamond Island or Cliff Island at all -- these are markets thin enough, in Little Diamond's case as few as three total housing units, that a single-digit annual sale count can make any "median" statistically meaningless. Do not treat an absent figure as zero, and do not accept an invented number in its place.

Dining and day-to-day services are genuinely thin on every one of these islands, which is honest rather than a gap in this page's research: Chebeague has the fullest small roster (Chebeague Island Inn, The Niblic, and Slow Bell Cafe), Great Diamond has Diamond's Edge Restaurant & Marina and the Diamond Cove General Store, Long Island has Byers & Sons Long Island Bakehouse and the Long Island Store, Cliff Island has the seasonal Cliff Island Store & Cafe, and Little Diamond has no dining establishment of any kind. Confirm any of these names are still operating before relying on them, since small seasonal island businesses can close or change hands quickly.

Whichever of these five islands you are evaluating, verify current ferry schedules and fares directly with Casco Bay Lines (and, for Chebeague, also the Chebeague Transportation Company), confirm any property's land area, tax status, and current population trend with that island's own town office or the City of Portland's assessor as applicable, and work with a Maine-licensed real estate professional familiar with island transactions specifically. If Peaks Island itself -- rather than one of these five other islands -- is what you are researching, see this site's dedicated Peaks Island neighborhoods page instead. Nothing on this page is real estate, financial, or legal advice.