Based on current services, in China you can go twice as far in half the time:

  San Francisco - Los Angeles:   620 km, train time 9:00 hr
  Beijing       - Shanghai:    1,320 km, train time 4:30 hr

Prices in China are slightly higher:

  San Fran - LA:        $53 lowest;  $65 average
  Beijing  - Shanghai:  $80   (553 CNY)

Averaged for $/km CHina would be 20-35% cheaper.

https://www.wanderu.com/en-us/train/us-ca/los-angeles/us-ca/...

https://www.chinahighlights.com/china-trains/beijing-shangha...