Can we trust Geography?
"On many maps of the United States, the states of Colorado and Wyoming appear to be rectangles.
Indeed, the enabling legislation creating the two states specifies their extent strictly in terms of lines of latitude and longitude, rather than rivers, mountain divides, or other geographical features. Wyoming stretches from 41?N to 45?N latitude and from 104? 3'W to 111? 3'W longitude. Colorado's borders lie between 37?N and 41?N latitude and between 102? 3'W and 109? 3'W longitude. Originally, the lines of longitude were measured west from Washington, D.C.
However, on the surface of a sphere, although lines of latitude are parallel, lines of longitude converge as you go north or south away from the equator. So, the northern border of each state is a little shorter than its southern border. The difference for Colorado is about 21 miles.
Hence, to a first approximation, both states appear to be trapezoids rather than rectangles, though on a curved surface. A trapezoid has one set of parallel sides."
mathtourist.blogspot.com/2007/08/rectangular-states-and-kinky-borders.html