Man - you gonna have to do 'bout 100 miles a day.

A direct shot in the west - -

Kansas -
US 24, KS 25, US 36, KS 27

Nebraska -
NE 27, US 34

Colorado -
US 34, CO 61, CO 14, US 40

Utah -
US 40, US 191, US 6, UT 96, UT 264, UT 31, US 89, UT 116, UT 132, US 6, US 50

Nevada -
US 50, US 395, NV 88

Calif -
CA 88, CA 104, E-13, CA 12 (or back roads)

Take a look on an atlas.