Moderator note: reply is to a topic inactive for 16 months:
Here is a summary of where I had internet access via AT&T on the California Zephyr from Chicago to Emeryville. I started tracking it from eastern Iowa border. I did have good success through much of Illinois.
Border of Iowa to omaha almost nothing
80 miles North East of Denver good
Denver to about 25 west good
Spotty from 25 west of Denver to winter park
Winter park to Granby almost nothing
Granby to 10 miles outside Glenwood springs nothing
Glenwood springs to Rifle good
Rifle to Grand Junction service real good until abrupt stop 20 East of Clifton.
Service resumed 5 miles easy of Palisade. Good to 20 miles west of Grand Junction
From the i70 and route 6 intersection service is very good until 30 mikes west of Green Valley, UT
Good 20 mikes from Price, UT
Winnemuca, NV to just NE of Fallon, NV good
Abeam Fallon to Reno good
Reno to Trukee, CA good
Trukee to 50 miles from Colfax good
Service again from Dutch flats to Colfax low signal but there
Colfax to Sacramento. Spotty until Applegate then solid and good to Sacramento
Sacramento to Bay Area - Good Coverage