Maine Borders: States, Map & Complete Guide

New Hampshire and Maine are separated by a border located on Maine's western edge. The boundary runs roughly north-south from Quebec in the north to the Atlantic Ocean in the south.

The Maine-New Hampshire border extends for about 180 miles. The border follows the Salmon Falls River and Piscataqua River in the south, then continues as a land boundary through forests and mountains in the north. Maine counties along this border include York, Oxford, Franklin, and Somerset. On the New Hampshire side, Rockingham, Strafford, Carroll, and Coos counties sit along the border. Portsmouth, New Hampshire and Kittery, Maine sit across from each other at the southern end.

Quebec and Maine are separated by a border located on Maine's northwestern edge. The boundary runs roughly northeast-southwest through remote forest and mountain regions.

The Maine-Quebec border extends for about 180 miles from New Hampshire in the west to New Brunswick in the northeast. The border passes through largely uninhabited wilderness in both Maine and Quebec. Maine counties along this border include Franklin, Somerset, and Piscataquis. The border region includes mountainous terrain and the headwaters of several major rivers.

New Brunswick and Maine are separated by a border located on Maine's northern and northeastern edges. The St. John River and St. Croix River form portions of this boundary, creating natural water borders.

The Maine-New Brunswick border extends for about 430 miles, making it Maine's longest international border. The St. John River forms much of the northern border, while the St. Croix River creates the eastern section near the coast. Maine counties along this border include Aroostook, Penobscot, Washington, and others. Major crossing points include Madawaska, Fort Kent, Houlton, Calais, and Eastport.

The Atlantic Ocean forms Maine's eastern and southern boundaries, creating one of the most distinctive and rugged coastlines in the United States. The coastline stretches from New Brunswick in the northeast to New Hampshire in the southwest.

Maine's Atlantic coastline measures about 228 miles along the general shoreline, but the tidal shoreline (including all bays, inlets, and islands) extends for approximately 3,478 miles. The coast features rocky cliffs, sandy beaches, numerous harbors, and over 3,000 coastal islands. Major coastal cities include Portland, Bar Harbor, Rockland, and Kennebunkport. Acadia National Park sits on the coast. Maine's coastline is famous for its lighthouses, fishing villages, and lobster industry.