And the rise of the Interstate Highway System seems almost impossible to have prevented.
Not necessarily. But yes there is a limit on how much rail infrastructure can do but preventing the Interstate Highway System is not entirely ASB and it brings forth some big time cultural butterflies (which in turn affect political ones) that are usually underrated.
Lets say as it was proposed that the funds go instead into defense and so the construction of the IHS is delayed. If you delay it long enough railroads have stayed in used maybe even expanded which takes care of short distance travel. Delay it to the 60s and flight gets developed even more taking care of longer distance. With less competition from the IHS these modes of transportation get developed further.
Interstate Bullet Speed Trains might be around, more common, and developed earlier. And America's fear of flying (which was there before 9/11 is not there. Airlines do better and cheap airlines such the as small European ones in OTL develop.
All this is only to help the IHS from ever developing. Hold it off long enough and people wont see its need.
However the most important factor comes in how it will affect the designs of American cities and as a consequence American life.
Though the head of General Motors never said his famous quote of "What is Good for General Motor's is Good for America" the spirit of such quite is still there in OTL. In a TL with no (or a smaller) IHS you do not have the giant automobile corporations that ran America for a very long time. This translates to less problems with the oil industry. Once you have high-speed electric trains there is very little reason to delay the search for alternate fuels as it has happened in OTL. Though the larger and more powerful airlines companies ITTL might throw a fit.
Relations with oil exporting countries are completely different and that is a huge butterfly.
In everyday life things also change. For one less people have cars. This means that edge cities like Los Angeles and Atlanta (and every mid western city) develop differently. Instead of becoming Drive-Thru paradises they are built more compact centered around public transportation and over all better designed for community living. People will live closer to work if they do not have the Highway that connects them from the suburbs to downtown. The suburbs have unfortunately already appeared and they are one of the major causes for the ISH to develop as it did. But without the IHS hopefully their appeal is soon disappears as people cant stand living that far from work.
Along with the Intestate Highway System, Fast Food with Drive Thrus have helped homogenize America to the point in which it is today. They are both very interconnected in their history and have been very important in the development of American culture in the last 40-50 years.
Indeed without the IHS the west will be very different. It would be less settled but that will not stop from LA, San Fransico, Seatle from becoming major cities. San Jose which is now bigger than San Francisco will very likely stay smaller as it is a prime example of an American city that benefited from the IHS, the suburbs, the Drive Thrus, and the Edge City design.
Depending on the effect of the railroad system even food will be very different. Distinctive local food will not disappear as they did in OTL for the most part rather than being able to fish a lobster in Maine and ship it to California where it will be eaten. I know you can get a Miane lobster in Australia nowadays but the idea does not become popular until much later on.
Over all it is a major POD, and a cultural timeline on it would be very interesting to read.
(BTW Edge city refers to a city where people live on the edge, ei the suburbs, and work in the center, downtown. Usually instead of having its poor neighborhoods on an outer belt it has them near downtown. It been the prominent design employed in American cities since the construction of the IHS)