How Long Is Maine’s Coastline? 228, 3,478 or 5,500 Miles

Maine’s coastline is 228 miles, 3,478 miles or more than 5,000 miles long, depending on who measured it and what they counted. The two official figures come from different federal agencies, and two older estimates from the 1990s are higher still. Here is where each number comes from and why they do not agree.

The rocky coast at Acadia National Park, Maine.
The rocky coast at Acadia National Park, Maine. Photo: Pos, Robert H, U.S. Fish and Wildlife Service, Public domain, via Wikimedia Commons

The numbers, source by source

  • 228 miles. The Congressional Research Service uses a standard “general coastline” method that leaves out bays and inlets, according to a December 2025 Gigafact fact brief from the Maine Trust for Local News.
  • 3,478 miles. NOAA’s figure, which includes tidal inlets and other intricate features, per the same brief. NOAA’s Maine page lists it, citing Shoreline Mileage of the United States.
  • 4,500 miles. A Down East note from May 2002 said Maine’s coastline grew from 3,500 miles in 1960 to 4,500 miles in 2002, when bays, islands and inlets were included.
  • 5,200 miles. A 1993 Portland Press Herald story reported a computer calculation from U.S. Geological Survey charts by Christopher Kroot of the Maine Department of Environmental Protection.
  • 5,500 miles. An August 1993 Down East article said researchers at the College of the Atlantic, using satellite photos and GPS in a computerized mapping system, found 600 more miles than earlier estimates.

Maine versus California

The same two federal figures drive a popular claim that Maine’s coastline is longer than California’s. By NOAA’s measure, Maine’s 3,478 miles edges out California’s 3,427, per the Gigafact brief. By the Congressional Research Service’s method, California’s 840 miles is more than three times Maine’s 228. The brief concludes that Maine’s coastline is not three times longer than California’s under any official measurement.

An early chart of the coast of Maine, from the Library of Congress.
An early chart of the coast of Maine, from the Library of Congress. Photo: Porter, Seward; Moody; T. Moore’S Lithography, Public domain, via Wikimedia Commons

Why the sources disagree

  • What counts. The 228-mile figure ignores bays and inlets. The larger numbers follow them, and the 2002 note says its total included islands as well.
  • How it was measured. The 1993 estimates came from computer analysis of survey charts and from satellite and GPS mapping, while the NOAA figure comes from a federal shoreline mileage report. The sources do not all say what map scale they used.
  • When it was measured. The 1960 and 2002 figures differ by 1,000 miles, and the 2002 note ties the larger total to including bays, islands and inlets.
  • What we could read. We read only the abstracts of the Portland Press Herald and Down East items, not the full articles.

Maine coastline length: FAQ

How long is the coast of Maine?

NOAA lists 3,478 miles of coastline. The Congressional Research Service’s general coastline figure is 228 miles, and 1990s estimates ran from 5,200 to 5,500 miles.

Is Maine’s coastline longer than California’s?

By NOAA’s figures, slightly: 3,478 miles to 3,427. By the Congressional Research Service’s, no: 228 miles to 840.

Why are there so many different numbers?

They count different things. Some follow every bay, inlet and island, while the general coastline method does not.

Our details come from the Gigafact fact brief, NOAA, the Portland Press Herald abstract and two Down East abstracts, 1993 and 2002. We have not independently verified these figures, and agencies update them from time to time.