The ones in the west were based on latitude and longitude. The rest were drawn (or redrawn) because of a combination of economic, political, legal battles, treaties, and geographic reasons.Here is a book on the subject if you really want to knowhttp://www.heritagebooks.com/mm5/merchan��
The ones in the West, many of which have very straight borders, were set on township and line systems, which weren t in existence in the 18th century, or the first half of the 19th, either. Many of those really crooked lines follow rivers...the older way to set borders was to follow a river or other natural feature. Once the borders were established, there were political and economic and social reasons not to go back and re set them.
becouse when they were claiming their terretory they marked their territory using land marks, such as mountains and rivers...so instead of making a line across they simply said ok this side of the river is (say georgia) and that side is another state.....and thats why they are all wavy...and the straight ones were flat lands so it was easy for them to simply make a straight mark