I thought about that. I’d certainly agree with the cold war aspect. But not so much with the suburbia. With the housing shortages, I don’t associate the post war 1940s with surburbia the same was as the 1950s. The automobile shortages as production ramped up and then had to fill pent-up demand. Then there’s the various strikes right after the war. Though that’s a brief era.
Well, I’m not saying that the late 40s were actually the same as the 50s, in terms of what sorts of things were actually happening in the culture in the late 40s as opposed to the 50s, just that in our modern popular memory and imagination the late 40s and 50s get lumped together.
Though certainly there were plenty of material shortages and associated problems that persisted for a time post-WWII, there was, from what I’ve heard, a huge feeling of understandable relief at the war being over, as well as a feeling that we had ‘solved’ the problem of war once and for all, just like we thought we had after WWI (or, as it was originally known, “The War to End All Wars” 
).
That immediate post-war feeling of euphoria and optimism, that the future was this shining road paved with gold leading to a peaceful, prosperous future, I think led directly into the decade of the 50s. And because of that through-line, I think that any actual pop-culture distinctions between the late 40s and the 50s have been largely forgotten.
An indelible picture of the late '40s I have has probably been put in my mind by watching old movies: men in work clothes, wartime leather jackets, and battered fedoras all sitting in a seedy bar while drinking bottled beer and watching boxing matches on TV.
It’s worth having a look at the TV schedules of an era, since they’re a gold mine for cultural historians. My late brother was born in 1947. I came along eight years later, and he told me some stories about watching the tube when he was little. The one they had would go out sometimes, and our dad, who was in the US Army Signal Corps in WWII, had to fix it. I can imagine watching shows like Abbott and Costello, Laurel and Hardy shorts, Walter Lantz cartoons, and The Cisco Kid while sitting on the floor every Saturday morning. (I did the same in the '50s, but he did it when it was still fresh and new.)
Listening to radio shows from immediately after the war ('46 and '47), there was a fair amount of trepidation about how easy it would be to move from a war economy to a peace economy (e.g. retooling factories).
In addition to all of the above, I think of entering the nuclear age. Martin Amis’ essay “Einstein’s Monsters” encapsulates how huge (and awful) a change this was, especially subconsciously (including, in pop culture).
Yeah, I don’t think post war optimism kicked in until the mid-1950s. People almost immediately expected another, even worse war until about ten years later when they learned how to stop worrying and love the Bomb.
Amis mentions Saul Bellow. This novel takes place largely in the late 40s:
“The Adventures of Augie March can be seen as a dispelling of the traditional idea of an American hero. He is “the American chasing after self-exploration.”[5] He is given a background common of protagonists in inspirational American stories; “he comes from a poor family; he does not know the identity of his father; he refuses to be trapped by fine clothing, social position, or wealth,”[6] and he has plenty of “heroic qualities” such as his intelligence, compassion, and clear observation. However, despite these advantages, Augie does not truly live out the life of a hero. He has no commitments of his own, and merely goes along with plans and schemes developed by others.”
Yet, it was an era of American derring-do, for sure. Chuck Yeager breaking the sound barrier. The Berlin Airlift.
I also associate it with India falling apart into three pieces, and the founding of Israel. Not pop culture per se…but India, Pakistan, and Israel did eventually tie into the nuclear menace theme as well.
(This was balanced by the first stirrings of more workable efforts toward “one-world” globalism…the UN sticking as the League of Nations had not; France and Germany forging a trade pact that would later become the European Union…and, the baby boom demonstrating outward optimism over the background unease.)
Well, again, my theory (however right or wrong) is not that the period between the end of the war and the 50s was factually all one homogenous thing culturally, just that that period is perhaps lumped together, now, in the modern popular consciousness and imagination. That is the OP question I was trying to answer:
Also, in addition to the optimism I mention, the dark flip side to that coin, as mentioned by JKellyMap and others, is the beginning of the nuclear age and the rise of Cold War tensions. Those issues had clear underpinnings from the immediate post-war era, and though they may not have fully crystallized until the 50s, I think may also be lumped together as part of the overall popular culture of mid 40s- 50s, in the modern popular imagination of today.
Interesting you should mention the nuclear age. A few hours ago, I was watching a period film titled Nuclear Power Can Be a Force for Good, in which the inhabitants of a small town in the American Southwest were largely against the government opening a nuclear plant nearby. The townsfolk were convinced nuclear power was evil because of The Bomb (one man had been to Hiroshima immediately after the war ended). They protested to their Congressman but changed their minds when they found out nuclear medicine might save a little girl who was dying of a brain tumor.
There was a connection here; Harold Russell. Russell appeared in The Best Years of Our Lives and won two Oscars. He was also heavily involved in veterans’ groups. When Truman fired MacArthur, Russell went on a national tour to veterans’ groups, defending Truman and the principle of military subordination to civilian authority.
In the movie Thunder Road, bootlegger Robert Mitchum is trying to convince his mechanic brother to go legit, suggesting an engineering career, and predicting that “pretty soon, the engineers are going to have all the houses wired to nuclear power”.
I don’t think there was a late 40s. The 40s started with Pearl Harbor and continued through WWII and the aftermath. Then the 50s started early and kept going until the 60s started in late 1963.
I think the reason the late 40’s get lost was because it was the pause between two fights. Yes, so much of the 50’s was set-up in the 40’s but it took the Korean War to really solidify the pattern for the Cold War and the geo-political pattern of the next 45-50 years. Before Korea, the Soviets were just problematic with trying to work out the Marshall Plan and other post-war realities. But once the T-34’s rolled into South Korea, the commies became The COMMIES.
Posters are conflating two different things.
Some are talking about pop culture events that took place in the late 1940s. Some are talking about pop culture of today looking back to the late 1940s. Seems to me that the OP was asking about the latter.
Posters aren’t finding much current pop culture about the late 40s because there is next to none. It’s an alcove between the war and the fifties. Nothing was defined. The era looks like bunches of moving bodies - servicemen coming home, factory workers looking for new jobs, women becoming mothers (1946-1949 saw almost 14 million babies in a population that reached 140 million in 1950), everybody looking for housing because the suburbs haven’t boomed yet.
As with the suburbs, lots of things took root in the late 1940s, but only historians and arborists care about roots.
Well, it was a nice moment for teenagers. They didn’t even exist as a species until the war made them visible through the absence of young adults proper, but as the 40s became the 50s, those mildly annoying bobby-soxers were replaced by menacing juvenile delinquents.
Also the cars. Back in production after the war, there was a brief period of resumption of the basic 1930’s unibody: big, lumpy mounds of steel before things went wild with fins and chrome.
Remember when the Puerto Rican nationalists were shooting from the gallery in Congress, and tried to kill Truman when he was staying at Blair House while the White House was under repair? The Republicans made this joke: “What did one Puerto Rican sau to the other Puerto Rican? ‘Let’s go around the corner and shoot the shit.’”
There was a couple of years when the 1942 models were just put back into production because the auto companies didn’t have time to design something new, but once the new designs did start to emerge the styling looked like what most people would associate with the early 1950s. Actually I think that would apply to most things from that era. Show an average person a car, or kitchen appliance, or a train from around 1947-49, and they would most likely guess they were from the early 1950s.
I made that mistake myself when I saw a 1949 Chevy in a parking lot once. I initially assumed it was more like a '52 or '53, until I saw the license plate frame that called out the year. The styling just looked like what I associate in my mind with “early '50s car”. When I picture “1940s car” my mind conjures up something that looks like a holdover from the late '30s.
Well, I starred in was an extra in a noir film, titled Lonely Hearts about the Lonely Hearts killing spree that took place between 1947 and 1949. Director Todd Robinson’s grandfather was a NYC detective on the case.
Wardrobe dressed me (and my oldest daughter and ex, who were also in the film) in period 40s clothes and hairstyles. It was great fun, and the 1940s were depicted quite accurately. They put me in a lot of scenes, but most were cut from the film. 
It was fun conversing with the stars between takes. Travolta in particular was very friendly and chatty—he kept commenting on my snazzy hat and suit.
Unfortunately, the film tanked at the box office…but, it wasn’t my fault. Maybe if they kept more of my scenes in the movie it would have been a smash hit! 
There was a television show, Homefront, that ran on ABC for two seasons in the early '90s. The show was not that successful, staving off cancellation for one season before succumbing.