# Topics > Favorite Routes in North America >  What's the flattest route west-to-east across the US?

## Austin

Soon, I'd like to drive from San Diego to Florida. 

Trouble is, increasingly over the past 20 years, I've had trouble driving in or through mountains.(I don't get dizzy. I just feel anxious. Especially if a road is winding or sides of a road drop away steeply.)

Though I've done some online searching, I haven't been able to identify the flattest route across the US, west-to-east.

Is it I-10? I-40?

If both I-40 and I-10 offer the same level of elevation,which is less winding through the mountains? Which has more lanes?

(When driving through mountainous terrain, if I can keep to the lane the furthest from the side dropping away precipitously, I'm all right.)

Note that as I'll be driving alone, I plan on taking my time and stopping whenever and wherever I wish. That said, I'd like to keep the trip to 14 days, one way.

Please, can anyone advise?

Thanks!

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## Midwest Michael

Welcome to the RTA Forum!

You need to remember that even in the Mountains, all interstates are built to specific standards that limit sharp grades and turns and require wide shouldesr, so the curves and drop offs you talk about are practically non-existant even on the biggest of mountain passes.

I-10 is going to be your best bet. It doesn't completely avoid mountains (its impossible to do so on a cross country trip) but it does stay at the lowest elevations and would also be the shortest route for this trip.

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## glc

The hardest part of your whole trip will be I-8 between San Diego and El Centro.  It's a piece of cake from there all the rest of the way on the rest of I-8 and I-10.

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## Foy

> (When driving through mountainous terrain, if I can keep to the lane the furthest from the side dropping away precipitously, I'm all right.)
> 
> Please, can anyone advise?
> 
> Thanks!


Hello Austin,

While I am sympathetic to anyone with a mobility-limiting condition, your comment above caused my ears to perk up just a bit.

Whether it's along an uphill or a downhill segment of Interstate, occupying the left lane of an Interstate highway when not actively passing slower vehicles is often unsafe.  In some states, it's illegal, although it seems to be a more and more widespread habit in this day and age.

Still, the professional driving community (read: truckers) will likely crowd a "left laner" unmercifully until he/she yields the lane.  Common courtesy and good sense dictate you look in your mirrors carefully and often in order to ensure your presence in the passing lane does not unnecessarily or unsafely impede other drivers.

Foy

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