San Francisco to Laredo, TX - I-40 vs I-10 ?

[AZBuck]

We have technology to poke a 50 mile or so tunnel underneath Sierra Nevada mountain range if needed.

but it's probably not the technology

Well....there is the problem of supplying fresh air to the entire length of a 50 mile tunnel. Otherwise, it's going to fill up with CO2 and CO pretty quickly, and then it's just a race to see which kills the most drivers fastest.

Later Addition
For comparison, consider the Mont Blanc Tunnel under the Alps between Italy and France. It's 7¼ miles long, so only about one-seventh the length we're talking about. The toll for the tunnel is $50 one way at current exchange rates, which if linearly extrapolated would mean a toll of $350 for a 50 mile tunnel under the Sierra Nevada. In March, 1999 a truck caught fire near the mid-point of the tunnel. The fire lasted 53 hours, spread to 35 other vehicles, created intense heat and toxic fumes, and killed 39 people.

AZBuck