>>On to a more serious question: During the heyday of passenger train travel, you would have to chaged trains–even stations in some cases–on an east-west trip, of any length, in Chicago, St. Louis, or New Orleans. >>dougie_monty
In the “heyday” of passenger train travel, there was no Amtrak. Individual railroads handled their own passenger service on their own tracks (+rail right of ways +stations).
Early railroads in the east largely terminated at Chicago. Their lines (for the purposes of discussing transcontinental travel) simply did not extend beyond Chicago. Beyond Chicago, large western railroads completed the trip to the west.
Some of the railroads from the east to Chicago had premium or limited service which became famous as “20th Century Limited” (NY Central RR/NY to Chicago), “Broadway Limited” (Pennsylvania RR/NY to Chicago) and the “Capitol Limited” (Baltimore & Ohio RR/Washington to Chicago). From Chicago west some of the more famous premium trains were the “Super Chief” (A.T.& Santa Fe RR/ Chicago-LA), the “California Zephyr” (Burlington, Rio Grande and Western Pacific RRs/Chicago to Oakland) and the “Empire Builder” (Great Northern RR/Chicago to Pacific NW)
In Chicago, most railroads had their own terminal. Passengers had to detrain and switch to another terminal for the rest of their journey. Eventually, several railroads shared terminals (PRR, Burlington and others shared Union Station, NY Central and others shared Lasalle Station, B&O, C&O and others shared Grand Central Station, and Santa Fe and others shared Dearborn Station), but you still had to at least switch railroads, if not stations. Not until 1956 was it readily possible to enjoy transcontinental through service (via agreements between certain eastern RRs and certain western RRs.)
The eventual failure of private passenger service led to the takeover of virtually all long distance passenger travel (with a couple notable early exceptions) by Amtrak. Whatever its failings, Amtrak has consolidated passenger service (using the tracks of the private freight railroads except in the Northeast Corridor) and passenger stations, permitting through service. They even adopted (or co-opted) some of the old names, including the Capitol Limited, the California Zephyr, the Super Chief (now the Southwest Chief).
>>I asked some people I know about this; one said railroads deliberately did this to make train travelers pay more; another claimed it was because the “Superliners” used in the West were too big for Eastern railroad tunnels. Any answers from the Teeming Millions?>>
The Superliners are relatively new and of course were not around in the heyday of passenger service. The higher clearances they require make them virtually unusable in northeastern tunnels or under the catenary of the old PRR line (although the Capitol Limited route can handle the Superliners). For this reason and others, you still have to change trains in Chicago, even if you buy a ticket from Amtrak for New York to LA or Oakland