Yahoo gives me two diff. ways from Chey. Wy. to Yellow. N.P. and AAA has a different way. Which is best?

Least travel time is priority. Driving is at night.

1.I-80 west to I-15 north to rt. 20 in Idaho Falls to the park.

2.I-25 north to Casper, rt. 20 west through Greybull to the park.

3.I-80 west to rt. 287/26 through Grand Teton N.F. to the park.

going thru casper is your best bet... you're in the high plains going this way.. no mountain roads, no crazy winds or weather.... just a flat incline most of way...

I always use Map Quest, they are the best, and I am an OTR truck driver. Good Luck.

Here's mapquest's version, going in the east entrance.

http://www.mapquest.com/directions/main.adp?do=nw&go=1&r=f&aoh=&aot=&aof=&1a=&1c=Cheyenne&1s=WY&1z=&1y=US&1l=nLx5H7lYFbQ%3d&1g=EAstZ6tO%2byZjfXDxhvkmvg%3d%3d&1pn=&1pl=&1v=CITY&1ffi=&1n=Laramie%20County&1qn=&2a=&2c=&2s=&2z=&2y=US&2l=&2g=&2pl=&2v=COUNTRY&2ffi=&2n=&2qn=yellowstone%20national%20park&panelbtn=2&1qc=&q=yellowstone%20national%20park&2pn=yellowstone%20national%20park&2sb=Yellowstone%20National%20Park%2dEast%20Ent%7cEast%20Entrance%20Rd%7cYellowstone%20National%20Park%7cWY%7c82190%7c444895%7c%2d1100015%7c307%2d344%2d7381%7cUS&2qc=Parks

I-80 west to hwy 191 north its about 9 hours this way. I take it every year.