40th parallel north

The 40th parallel north is the southern baseline for Canada's National Topographic System.

The parallel 40° north formed the original northern boundary of the British Colony of Maryland.

A subsequent royal grant gave the Colony of Pennsylvania land north of the 40th parallel but mistakenly assumed it would intersect the Twelve Mile Circle, which it does not.

The parallel goes directly through the John Glenn Columbus International Airport, with runway 10L-28R lying immediately north of the line, runway 10R-28L lying slightly south of it, and the line going through the northernmost edges of the terminal.

Thistle, Utah, a ghost town since 1983, is slightly (30 seconds or 956 metres (0.594 mi)) below 40° north.