as our old RV (and us) don't like crossing mountains... what is the lowest altitude going from the west coast to the east coast across the mountains. i was told that I10 is flat but elpaso is 4000 f...
I-10 has the least grades to climb across the country. The climb up to El Paso is very gradual over a long distance. Hardly noticeable. Here are the grades I'm aware of on I-10.
East of Indio, CA. About 2-5% for 15 miles. The 5% parts are very short. Texas Canyon, AZ. About 5% for 2 miles. KerriVille, TX. 7% grade 1 mile. Wallace Tunnel, AL 7% 1/2 mile.