Prime Day Sale

https://www.amtrak.com/primeday

"Enjoy this 20% off discount when you travel on a Tuesday, Wednesday or Thursday between August 5th and November 13th."

Book by 7/11. It's hit or miss... you don't find out if it's good on any particular trip until the final page before booking. Despite the name, it has nothing to do with Amazon except for the timing, I guess.