This obviously raises further questions, which are
- when the train staff were transferred to Amtrak
- when the rolling stock was transferred to Amtrak
- when the ticketing operations were transferred to Amtrak
I think the rolling stock transferred over early (before A-day?), since the rolling stock contributions were part of the process of joining Amtrak and being relieved of the obligation of running passenger trains on their own account. I assume the ticketing transferred over *on* A-day. But I think the train staff changed employers slowly... anyone know?
The initial operation was with the RRs rolling stock for operational reasons as well as it took time to inspect the equipment and pick what they wanted (lots from Santa Fe, not much from Penn Central), they just continued to do what they did the day before in most cases, although where the railroad infrastructure was lacking, they made changes almost immediately. An example is in Los Angeles where SP had closed their coach yard in 1968, and most servicing was done in San Francisco and Oakland with minor service done right at LAUPT. Amtrak had Santa Fe do all coach yard work including former SP service almost immediately for a number of reasons including the initial operating pattern with the Daylight/Starlight in particular. The rolling stock transfer took place fairly early though, and ownership was transferred around 1972, IIRC. The transfer caused a lot of silly problems. Penn Central coach yard crews didn't know what to make of UP equipment for instance. But the Rainbow Era, which really started when Amtrak assumed ownership of the passenger cars, was pretty entertaining. I remember having a SCL lounge car on a San Diegan I rode in the fall of 1973.
The on board service staff started transferring around 1973 or 1974 IIRC. It took awhile for Amtrak to establish the infrastructure, there were union issues to deal with. That took place somewhat gradually.
Reservations happened fairly early. It was the highest priority to do early, as Amtrak using the RR's reservation bureaus meant Amtrak had a number of different numbers to call (if you were taking an ex-SP train, you called the old SP reservation line, if you were taking Santa Fe, you called Santa Fe's number) and a wide variety of policies around credit card acceptance, SP didn't take credit cards while Santa Fe did, IIRC. They wanted to establish a single presence, so getting that unified was a high priority. I think they got reservations together by sometime early in 1972. You could tell by looking at the early timetables, because they'd stop listing all sorts of different numbers to call for different services.
However, Amtrak used RR station agents at small stations for a LONG time, into the 1980s, although they'd use Amtrak's reservation system. Think how Amtrak arranges with VIA to use VIA agents in Vancouver, Toronto and Montreal now. That only dried up as the RRs closed their freight agencies, and Amtrak either had to put their own staff in or let the station go unstaffed (which was the preferred option in most cases).
The last to cut over was the T&E crews. That started taking place in the early 1980s. Again, there were union and operational issues. I had a friend who was a conductor with Santa Fe at the time who went to Amtrak. They had the right to transfer back to Santa Fe holding seniority for a certain period of time (a year or two I think). The RRs were paying mileage, and Amtrak was going to pay hourly and establish longer crew districts. That meant longer hours for the same (or often less) pay.
This is all from memory as a regular Amtrak rider and follower from the time.
But the important thing to remember is that at the beginning, Amtrak didn't have any operational presence at all. The RRs just did what they had been doing servicing, ticketing and running trains, somebody else just paid all the expenses and kept what revenue there was. That only changed gradually.