Maine’s only state neighbor is New Hampshire, which sits between Maine and Massachusetts. The two states are separated by about 150 miles as the crow flies.
Geographic Context
Think of New Hampshire as the middle child in this New England family. Maine anchors the northern tier of the region, while Massachusetts sits to the south. The Piscataqua River, which flows into the Gulf of Maine, historically marked the colonial divide between what’s now Maine and Massachusetts—though today it’s the official border between Maine and New Hampshire.
Key Details
| Border Feature | Length or Description | Notes |
|---|---|---|
| Maine–New Hampshire Border | 138 miles (222 km) | Includes 16-mile water boundary along the Piscataqua River |
| Maine–Massachusetts Proximity | ≈ 150 miles (241 km) as the crow flies | Between northern Maine and western Massachusetts |
| Piscataqua River Channel | Navigable for commercial vessels | Forms part of the Maine–New Hampshire maritime boundary |
| Canadian Border Adjacency | 611 miles (983 km) | Shared with New Brunswick and Quebec |
Interesting Background
Back then, Mainers felt Massachusetts ignored their needs—economic, military, you name it. That frustration led to a push for independence. The Missouri Compromise of 1820 made it official: Maine became the 23rd state (and a free one), while Missouri entered as a slave state to keep the Senate balanced. The Piscataqua River, which once divided colonial territories, now serves as a clear marker between Maine and New Hampshire. These days, the river isn’t just a boundary—it’s a working waterway supporting shipyards, fishing boats, and protected habitats like the Great Bay National Estuarine Research Reserve.
Practical Information
That’s where the Piscataqua River meets the Atlantic. From there, you can hop on a seasonal ferry to the Isles of Shoals—some of those islands actually sit in Maine waters. The National Park Service keeps an eye on them. Prefer driving? The New Hampshire Coastal Byway offers stunning views along the estuary. Crossing into Canada? The closest land crossings are Calais–St. Stephen and Van Buren–St. Leonard—check CBP for real-time wait times. Train travelers can catch Amtrak’s Downeaster in Wells, Maine, which connects Boston to the southern coast. Honestly, this is one of the prettiest stretches of the Northeast. Don’t miss it.
