They would have seen a lot of soldiers returning home from Europe traveling in their direction. "Demobilization" and return took a couple of years. Almost all of them would have been traveling in uniforms or pieces of uniforms; rationing was over, but there was still a clothing shortage while factories converted and the supply chains filled back up.
Again due to rationing, most things would have looked a bit shopworn and threadbare. Necessary maintenance would have been done, but there was neither money nor manpower for paint and polish.
Some large percentage of the returning soldiers didn't go back to where they came from; many hopped a train and went somewhere else. Most of them went to large cities, where they thought they might find a decent-paying job.
During the war, the US wasn't *quite* operating under a Soviet-style centrally planned economy, but it was pretty close. After the war a lot of businesses had grown too lazy filling government contracts to compete successfully in the free market and went under. Hundreds of thousands of returning soldiers were flooding the labor pool while the number of available jobs shrank sharply. In the first few years after the war the economic situation was ugly; the Depression-era bread lines didn't return, but it was very close for a while. A lot of the people traveling in 1946 would have been worried about the future and feeling lucky they could afford a train trip.
Among this, they would have seen the first postwar automobiles on the road; mostly continuations of prewar models, but brand new. And some elaborate new clothing styles for women.
During the war imports from South America had been rare; diners might have welcomed food items that had been rationed or unobtainable earlier.
The news would have talked a lot about the Nuremburg trials, the Soviets absorbing Eastern Europe, and friction in partitioned Berlin. The media wasn't much interested in the Pacific. There was a lot of talk about that new "United Nations" organization, but people who remembered the League of Nations weren't impressed.
If their trip takes place in the winter of 1946, that winter was early and freakishly cold. Much of America was snowed in. Not that big a deal in America, but tens of thousands of people died of it in Europe and the USSR.
Few roads outside of urban areas were paved. Dirt was the most common, gravel for "improved" roads. Cars and trucks generally moved around 35 mph, and most of what was on the road were prewar and in poor shape.
The Rural Electrification Program was still underway, but outside of towns, the countryside would have been mostly dark. Telegraphy was still an important means of communication. Most towns had phone service of some sort in 1946, but not all of them were hooked up beyond the local area. Even when they were, a three-minute long distance call might take a day's pay.
Gas lights were still common in rural areas; in larger cities they might be considered old-fashioned, but weren't all that unusual.
The trains rolled seven days a week, but west of the Mississippi most of the country came to a halt on Sunday. Even if a "blue law" wasn't on the local books, most businesses were closed anyway. Your character probably couldn't buy a cup of coffee, clean underwear, or a dime novel unless he bought it on the train or at a shop at the station. Likewise, after five or six o'clock most businesses closed up during the week.
If your story involves crime, most railroads had their own officially recognized police. (and still do!) Local police didn't always wear uniforms, and often used their personal vehicles.
Segregation was still in effect in 1946. Most places had separate bathrooms and drinking fountains for blacks and whites, some carried things even further. If you've ever wondered why most Interstate rest stops have two men's rooms and two ladies' rooms, or older theaters or public buildings have four bathrooms, that's why. It would have been more pronounced east of the Mississippi.
Television existed in 1946, but mostly in highly urban areas. Radio was common; wider spectrum than we have now, including short wave. It wouldn't have been unusual to pull in a station in a foreign country on a good night. Recorded music tended toward blaring horns since it was easier to record than strings. Newspapers were everywhere; even very small towns usually had a paper. Many towns had several, and often both morning and evening editions. And there would have been county, regional, and state newspapers, as well as newsletters, pamphlets, magazines, etc. A "newspaper stand" in 1946 usually offered a wide selection of printed matter.
Outhouses were still the rural norm in 1946. The train stations had indoor plumbing, and so did larger public buildings. The bathrooms were much larger than nowadays; most of them had an "attendant" whose main job was to prevent vandalism and make sure the rubes knew not to use a convenient spot on the floor instead of the fancy porcelain fixtures. Since the traffic was high when a train arrived, there were a *lot* of urinals, sinks, and stalls. The stalls were huge by modern standards, usually with a sink and folding shelves; you would use them to take a sponge bath and change clothes on a long trip.
The unrestored train station bathroom I got to see some years ago was all tile, mostly in yellowy or pukey colors. Teeny hexagonal tiles, not the modern hand-sized square ones. The lighting fixtures were huge, elaborate steel chandelier things, like inverted Borg beehives. It also had a small office, presumably for the attendant, and a shoeshine stand.
That station had a large circular "information booth" in the middle of the lobby. Maybe 20 feet around. It wasn't in use when I saw it, but I imagine it was probably a "gift shop" or "sundries stand", or maybe a sandwich stand, before it was an information booth. On the wall facing the tracks was the ticketing booth; maybe 25 feet long, able to service a dozen queues. It looked like a booking desk at a minor airport. Lots of old-fashioned electrical equipment on the back wall, presumably communications with other stations and some sort of tracking for train position. Some of it had been removed by the time I saw it.
More giant Borg chandeliers in the lobby. Other than those and the floor, everything was dark-stained wood - benches, walls, trim, doors. I thought it was pretty sad and gloomy, but back in 1946 it probably looked like a happenin' place.
Go over to Google Books and hit the Popular Mechanics and Popular Science magazine archives. There's a lot more about daily life there than you might expect for what were supposed to be technology magazines.
