From a jurisprudential standpoint, there are two interesting milestones. The first is Schenck v. U.S. (1919); the second is Dennis v. U.S. (1951)

August 1917 - Schenck, the secretary general of the Socialist party, hands out leaflets encouraging people not to participate in the draft.

October 1917 - the October Revolution

March 1919 - the US Supreme Court hands down Schenck v. U.S., holding Schenck (referred-to by Holmes as "Comrade Schenck") guilty of violating the Espionage Act.

Holmes concludes:

But it is said, suppose that that was the tendency of this circular, it is protected by the First Amendment to the Constitution. Two of the strongest expressions are said to be quoted respectively from well known public men. It well may be that the prohibition of laws abridging the freedom of speech is not confined to previous restraints, although to prevent them may have been the main purpose, as intimated in Patterson v. Colorado, We admit that, in many places and in ordinary times, the defendants, in saying all that was said in the circular, would have been within their constitutional rights. But the character of every act depends upon the circumstances in which it is done. The most stringent protection of free speech would not protect a man in falsely shouting fire in a theatre and causing a panic. It does not even protect a man from an injunction against uttering words that may have all the effect of force. The question in every case is whether the words used are used in such circumstances and are of such a nature as to create a clear and present danger that they will bring about the substantive evils that Congress has a right to prevent. (some internal citations omitted).

Schenck was decided at the same time and in the same manner as Debs v. U.S. Eugene Debs was a five-time socialist candidate for President who was convicted for protesting against WWI. Note - Debs was a socialist, but he was arrested and convicted not for socialism but for protesting the war.

Debs is notable because his highest vote-getting as the socialist candidate was in 1912, at 6%. His sentence was commuted in 1921 by President Warren G. Harding. I think this tends to indicate that at least in 1919 - 1921, there was not a lot of animus towards socialism, at least not nearly as would be later shown in the McCarthy era (or Dennis, discussed immediately below). However, it also indicates socialism was never really popular, at least politically.

Over the intervening years, Justice Holmes in particular changed course and argued for much stronger application of the First Amendment. What is very interesting is that Judge Learned Hand, one of the foremost judges never to make it to the Supreme Court, argued almost immediately that Schenck was wrongly decided. Hand was a strong proponent of the First Amendment.

But then in 1951 the Supreme Court decided Dennis v. U.S. There, the Court held advocacy of communist ideas violated the First Amendment. Judge Hand wrote the circuit court opinion, which was upheld and by most reasonable standards, this is a deviation from the "clear and present danger" standard because the Court found there was no need for success or possible success; the mere advocacy was enough.

The Supreme Court adopted Hand's rule:

In each case, [courts] must ask whether the gravity of the 'evil,' discounted by its improbability, justifies such invasion of free speech as is necessary to avoid the danger.

One school of thought to which I subscribe is that the basis for the Dennis opinion is the threat of government overthrow, which was thought to be a lot more real in 1951 than it was in 1914.

Edit - more: In other words, by 1951, the Supreme Court thought there was enough of a threat of violent overthrow of the government that it held the government could legitimately convict people for advocating socialist revolution. Thomas Jefferson would not be proud. But it does indicate, at least a little bit, the arc of fear of socialism from 1919 - 1951, which was on a decidedly upward trend.

Admittedly this response isn't ideal because it doesn't cover a lot of activity before 1917, but I'm taking a narrow reading of your prompt and saying "the rise of communist states" didn't happen until after 1919.

Edit as noted above.

you might be interested in the book an unfinished revolution which is made up of letters written between abraham lincoln and karl marx. lincoln was a great admirer or marx and the first international, and apparently saw parallels between the war to end slavery in the united states and the struggle for worker's emancipation more generally. i am in no way an expert on any of this, so perhaps someone else can add more helpful information, if they have it.

This is a tricky question, because while I'm unaware of substantial evidence that many Americans thought that Orthodox Marxism/Marxist-Lenninsm of the kind that characterized Russia's political system was thought to be a political problem by many Americans, a related but distinct phenomenon, Anarchism, was definitely considered a threat.

The United States had always prided itself on not having a distinctive class system (at least for whites) as the European powers did from the birth of the Republic until the dawn of industrialization. After the American Civil War, the character of the American economy and with it the character of American social life changed dramatically. There were now substantially fewer people who worked independently as small farmers, and many more people who earned a living by selling their labor to others. This created what Marxists (and others) call Class Tension. To many people who grew up in an America without much of a class system to speak of, this was frightening.

This was compounded by the fact that many of the newly arrived European immigrants from the late 19th Century into the early 20th were ethnically different from the "Old Americans." Immigration had previously been limited to Western Europe, and consisted mostly of Protestants (save for the Irish in the 1840s-60s.) The New Immigrants were dark skinned and came largely from Southern and Eastern Europe. Many of them were Catholic or Jewish. On top of that, they ate weird food! Many of males in this group had to perform hard labor for a living since they lacked the language skills to do anything else. These people didn't seem to fit in. And many of them were gasp! Anarchists!

Anarchists believed in worker's revolution just as Marx did, but they were much less scientific or theoretical about how their proletarian revolution would take place. Many of them believed in an idea called Propaganda of the Deed, which sought to inspire a spontaneous, mass revolution through acts of violence against prominent political and business leaders. The best example of this was probably Leon Czolgosz, the assassin of William McKinley and an anarchist influenced by the likes of Emma Goldman (though he was actually born in the United States to Polish immigrant parents). The fear of anarchism and its violent tendencies became a defining experience for a generation of Americans who saw their President assassinated by one of them.

Things really heated up, however, after the October Revolution in Russia which overthrew the Czar and led to the creation of the USSR. This coincided with another wave of anarchist violence, this time in the form of a mail-bombing campaign led by followers of an Italian immigrant named Luigi Galleani.

To put it bluntly, those Americans who knew anything about any sort of communism or hard leftism generally feared it deeply.

This dates back to the very beginning of the Soviet Union, so I don't know if this is what you are looking for. But there was the American intervention in Siberia during WWI. Here is an interview with historian Carl Richard on the subject:

Take us back to 1918 and why did President Woodrow Wilson decide to invade Russia, in the first place?

In one of the theories, he wanted to control the Trans-Siberian railway in order to overthrow the Soviet government. And the original reason for that was to get Russia back in the WWI, because the allies were under a lot of German pressure on the Western front. Of course, it didn’t work out that way. And yet the American troops stayed in Russia for 1.5 year. And then, I think, Woodrow Wilson came up with an idea that the main threat was not the Germans, but the spread of communism. 85000 American troops sent to Siberia thought that the locals would join them? That was their hope. Wilson was pressured for 6-7 months by Britain and France who were desperate to take the pressure off the Western front. Then about 70,000 Czechs passing through Russia and trying to get home fell into an armed dispute with the Communist government. Anti-Bolshevik government started springing up under the protection of the Czechs. So Wilson decided that there’s a chance to make Russian people rise up against the Bolsheviks, as long as intervening forces are their cousins, the Czechs. Read more: http://voiceofrussia.com/us/radio_broadcast/58461471/97037381/