United States Counties?

Okay, lets say this..Your in New York City, as you go through counties, it seems quick since they are small, 2 days later your in New Mexico, you noticed since the counties are big it takes kind of long to get out of one. So here's my question, why do counties get small as you go Eastward and counties get larger as you go Westward? http://en.wikipedia.org/wiki/File:Pctmexican.png Map of Counties. (Ignore the topic with Mexican-America Population Per county)United States Counties?
The traditional size was determined by:



The placement of towns and cities, occurring regularly even in the most vast and empty parts of the nation, recalls the 19th century rule that a county seat should be within a day鈥檚 buggy ride for every citizen.



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Counties defined before the 19th century would have been sized according to local wishes and maybe natural boundaries. Also, forests and streams in the east made travel more difficult so counties were naturally smaller than in the west. There were probably other influences, but that would be the mosty common reason for a county's size.United States Counties?
you can say the same thing with the size of the actually states, they are scaled together mostlyUnited States Counties?
the us was originally east of the oh valley. once we got the la purchase and the other documents, we were able to space everything out more. also because most of the eastern states were colonies and are somewhat the same as when they were founded so theoretically, they would be smaller.