Montana vs. New York: Which State Has the Longer Canadian Border?

Montana has the longer border with Canada.

Border Lengths

Why Montana’s Is Longer

• Straight-line longitude span: Montana’s northern border follows the 49th parallel for ~545 miles — the full width of the state.
• New York’s border is fragmented: ~200 miles along 45th parallel (Quebec), then ~280 miles along St. Lawrence River / Great Lakes (Ontario). Water boundaries are shorter than the full latitudinal width.

National Context

• Longest state-Canada border: Alaska (1,538 mi) — but not contiguous US.
• Longest contiguous US state-Canada border: Montana (545 mi).
• 3rd: Maine (611 mi) — wait, Maine is longer! Let's correct: Maine (611 mi) > Montana (545 mi) > Minnesota (547 mi?) — actually Minnesota 547 mi (including Lake of the Woods water border). Maine #1, Minnesota #2, Montana #3 for contiguous states.

Correction: Maine (611 mi) and Minnesota (547 mi) both exceed Montana. The original claim "Montana longer than New York" is true, but Montana is not #1 overall.

Border Character

• Montana: Prairie, mountains (Glacier NP), remote crossings, low traffic.
• New York: Urban (Buffalo-Niagara), river/lake, high-volume commercial (Peace Bridge = #2 US-Canada truck crossing).

So: Montana > New York, but Maine & Minnesota > Montana. The 49th parallel gives Montana its clean, long line.