The first knock-on (ISTM) is in 1918-1920, when there is no Red Scare. The Bolshevik regime was the first "revolutionary" government in the world. Both the Reds and their adversaries expected additional Red revolutions around the world in the immediate wake of Russia. This led to a degree panic in the US. H.L. Mencken summed it up: "Civil liberties under lock and key, and [US Attorney General] Palmer baying through the streets."
By mid to late 1920, it was clear that while the Reds and other radicals might commit isolated acts of violence (e.g. the Wall Street bombing), there was no danger of mass revolutionary action. The Palmer raids had followed the overwrought anti-sedition measures imposed during WW I, such as the American Protective League. The general people began to see such programs as unnecessary intrusions. The termination of all that was implied in by Harding's 1920 campaign slogan "Return to normalcy".
Thus there may be a smaller Republican landslide in 1920. I think Eugene Debs would still be in prison; he would still call for draft resistance during the war, which is what he was convicted for. But he might do better in the 1920 election, without "Bolshevism" drawing leftsts away from electoral politics.
Another possible major knock-on is the effect of no USSR on the world economy in the 1920s and 1930s. I've seen some inchoate suggestions that the separation of Russia from the world capitalist system was a significant cause of the Great Depression. If that is actually true, US elections in the 1930s would be very different.
The existence of the USSR contributed substantially to the rise of Nazism in Germany (as did the Depression). Take it away, and there is no Hitiler dictatorship, and no World War II. The experience of World War II massively transformed the US, of course. It should be noted that by the 1960s, the great majority of US political figures were WW II veterans.
After WW II, the existence of the USSR led to extensive US involvement in world affairs, with US troops permanently deployed around the world and fighting several wars. The Cold War required the US to build and maintain enormous military forces; in the 1950s, military spending was about half of the Federal budget. The whole history of the US in the later 20th century was dominated by the demands of the US role as leading adversary to the USSR. Also, with the USSR as nuclear rival to the US, the threat of nuclear war had immense impact on US culture and politics.
No USSR, all that goes away.
Unless, of course, some other aggressive dictatorship arises instead to play a similar role.
The great technical triumphs of WW II, culminating in the Manhattan Project and the atom bomb, spawned enthusiasm for "big science" in later years. Congress became willing to appropriate immense sums for Science, most impressively for NASA and the "Space Race". Without the Soviet threat and WW II, none of that happens.
A more subtle question is the effect of Communist "agents of influence" on US culture, including political culture. Some observers have noted that in the 1930s, Soviet agents were deliberately tasked with spreading damaging ideas in Western countries, including the US, to cause social disruption and general demoralization. For instance, they promoted "Modernist" architecture, with its penchant for barren, alienating public spaces and ugly buildings. Some of the memes they propagated have remained infectious right down to the present, and the people they affect have no clue that they are pulled by the strings of long-dead Communist puppet masters. I don't know myself how much this has affected poltiical culture, but I know some very smart people who see it clearly.
By mid to late 1920, it was clear that while the Reds and other radicals might commit isolated acts of violence (e.g. the Wall Street bombing), there was no danger of mass revolutionary action. The Palmer raids had followed the overwrought anti-sedition measures imposed during WW I, such as the American Protective League. The general people began to see such programs as unnecessary intrusions. The termination of all that was implied in by Harding's 1920 campaign slogan "Return to normalcy".
Thus there may be a smaller Republican landslide in 1920. I think Eugene Debs would still be in prison; he would still call for draft resistance during the war, which is what he was convicted for. But he might do better in the 1920 election, without "Bolshevism" drawing leftsts away from electoral politics.
Another possible major knock-on is the effect of no USSR on the world economy in the 1920s and 1930s. I've seen some inchoate suggestions that the separation of Russia from the world capitalist system was a significant cause of the Great Depression. If that is actually true, US elections in the 1930s would be very different.
The existence of the USSR contributed substantially to the rise of Nazism in Germany (as did the Depression). Take it away, and there is no Hitiler dictatorship, and no World War II. The experience of World War II massively transformed the US, of course. It should be noted that by the 1960s, the great majority of US political figures were WW II veterans.
After WW II, the existence of the USSR led to extensive US involvement in world affairs, with US troops permanently deployed around the world and fighting several wars. The Cold War required the US to build and maintain enormous military forces; in the 1950s, military spending was about half of the Federal budget. The whole history of the US in the later 20th century was dominated by the demands of the US role as leading adversary to the USSR. Also, with the USSR as nuclear rival to the US, the threat of nuclear war had immense impact on US culture and politics.
No USSR, all that goes away.
Unless, of course, some other aggressive dictatorship arises instead to play a similar role.
The great technical triumphs of WW II, culminating in the Manhattan Project and the atom bomb, spawned enthusiasm for "big science" in later years. Congress became willing to appropriate immense sums for Science, most impressively for NASA and the "Space Race". Without the Soviet threat and WW II, none of that happens.
A more subtle question is the effect of Communist "agents of influence" on US culture, including political culture. Some observers have noted that in the 1930s, Soviet agents were deliberately tasked with spreading damaging ideas in Western countries, including the US, to cause social disruption and general demoralization. For instance, they promoted "Modernist" architecture, with its penchant for barren, alienating public spaces and ugly buildings. Some of the memes they propagated have remained infectious right down to the present, and the people they affect have no clue that they are pulled by the strings of long-dead Communist puppet masters. I don't know myself how much this has affected poltiical culture, but I know some very smart people who see it clearly.