New York to California - best route

I-80 is the shortest, fastest route from NYC (or basically anywhere in the Northeast) to Oakland (or anywhere in northern California). Any alternatives (for example going to the end of I-70 then using US-50 to reconnect with I-80, or going to Southern California then north on I-5) will take more time. That's why all the truck traffic out of Northern California uses I-80 to reach points east.

For going to Southern California, you have many alternatives. For going to Seattle, you have alternatives. For Oakland, from the Northeast, it is I-80 or something that takes more miles and more time.