Zoomable Google Maps show the most interesting locations throughout the country where Amtrak trains switch between different lines, along with Amtrak routings serving various old Union Stations.

Los Angeles
Union Station opened in 1939, completing consolidation of all passenger trains.

Martinez To Port Chicago CA
Amtrak's San Joaquin trains mostly use a former Santa Fe route, but use former Southern Pacific trackage in the Bay Area, which required a new connection between the two railroads.

Sandpoint ID
The Burlington Northern merger resulted in track consolidation for two formerly competing railroads.

Salt Lake City
Different competing services and railroads were eventually consolidated, as Union Pacific emerged as the only railroad serving the area.

The Burlington Northern merger, along with development of the 1974 World's Fair, resulted in numerous route changes and consolidations.

The Union Pacific trackage in southeast Wyoming was not ideally suited for trains between Denver and points west. Amtrak service operated backwards between Denver and Cheyenne, until the downtown Cheyenne was replaced with a new outlying station at Borie.