Here's a PDF download (233 KB) showing what railroads were operating, voluntarily or at the insistence of the ICC, at the beginning of 1971, and how much of that Amtrak was unwilling to run: http://ctr.trains.com/~/media/impor...ger_trains_operating_on_the_eve_of_amtrak.pdf It's the appendix of the old Kalmbach book Journey to Amtrak.
I've used Amtrak between Slidell, LA and ALX/WAS between 1987 until I retired ten years later. Otherwise I had to fly to the west coast until I retired. After retirement, I've used Amtrak solely, NOL, LAX, SDL, WAS, WIL, NYP, BOS, RDW, CHI, and back to NOL . I'm planning another SDL/WIL later this summer. Guys/Gals, I like being recognized and befriended by AMTRAK crews on trips. One Thanksgiving, I was the only sleeper pax on board. On a later trip, most the diner and hospitality crew looked up and said "Hi Hank, glad to see you." Makes a big difference to have crew that treats you like family.
When first opened until a few years ago we used Metro here in STL and the system at Atlanta when flew in to visit family UNTIL the criminal element found it to be a lucrative target against ridership. I cannot CC on those trains so stopped using them. Wife and I had taken AMTRAK to KC from Hermann a couple of times so did not have to drive and find a place to park for venues at the P&LD events. That may likely stop with this Covid19 stuff shutting down the events. One time rode to STL, stayed at the near to river Hotel not far from the AMTRAK Station watched the fourth fireworks and enjoyed the downtown nightlife for a weekend then returned, since then once again criminal elements looking for easy marks in that area began increasing and we stopped going.