Why are states in America especially in perfect straight line?

http://maps.google.com/maps?f=q&hl=en&ie=UTF8&ll=37.09024, 47.167389,92.8125 -95.712891 & spn = & z = 4 & om = 1 & layer = c & utm_campaign = en & utm_source = en-ha-na-us-google-svn & utm_medium ha = more other border counties are strong and serrated, so there are boundaries in North America perfectly straight? theres some Africa too, but thats it the rest of world power Lins mathamatical then did they do if someone straightt go hand in hand with a ruler to measure it out?

Some countries follow the topography to create their residents. Flatter areas just draw a straight line. Montana has some right and some waves.

Empires of Steel – North Africa World War Two map editor feature