How far was racism the cause of American opposition to immigration in the 1920s?

In the 1920s, American opposition to immigration was driven by several factors, with racism being a significant one.  Most early immigrants to America were 'WASPs' (white Anglo-Saxon Protestants) from wealthier European countries like Britain, Germany, and Sweden.  But after 1890, more immigrants started coming from Eastern Europe and Asia.  These new arrivals worried many 'WASPs' because they looked different and had different cultures and religions.  A senator in the 1920s even said that these changes were turning Americans into "a race of mongrels." This fear was supported by people like Madison Grant, who in 1916 wrote a book claiming that northern Europeans were genetically superior.  He warned that the 'inferior' people from southern and eastern Europe and Asia would weaken America's genes.  Laws like Virginia's 1924 Racial Integrity Act, which said that even one drop of non-white blood made a person 'colored,' showed how deep these racist ideas ran.  This kind of racism is often called 'nativism' and was a major reason why many Americans opposed immigration. 

However, there were also other important reasons why Americans were against immigration.  Trade unions, for example, were worried that immigrants would take jobs away from American workers by accepting lower wages.  This economic fear was a big deal for many Americans who were already struggling to make ends meet.  The idea of losing jobs to newcomers added to their opposition. 

The trauma of World War I also made many Americans want to return to isolationism, which means staying out of other countries' affairs.  They wanted to go back to the Monroe Doctrine's idea that Europe should stay out of America's business and vice versa.  This wish to isolate themselves extended to not wanting new immigrants, who were seen as foreign influences. 

There was also a fear of an 'alien menace,' especially after the 1919 Communist revolution in Russia.  This 'Red Scare' made Americans afraid that immigrants, especially Italians, would bring communism and anarchism with them.  The rise of organized crime, with famous immigrant gangsters like 'Lucky' Luciano and Al Capone, added to these fears.  People thought that immigrants were behind much of the criminal activity. 

The new immigrants were often poor, couldn't speak English, and had different customs.  They tended to live in neighborhoods with people from their own countries, which made them seem even more separate from mainstream American society.  This separation increased ignorance and prejudice, making Americans even more opposed to these newcomers. 

Additionally, the sheer number of immigrants arriving in the early 1900s—13 million between 1900 and 1914—made many Americans feel overwhelmed or 'swamped.'  Cities grew quickly, and services like housing, schools, and hospitals struggled to keep up.  This rapid growth made people worry that the country couldn't handle so many new people at once. 

In conclusion, while racism was a major factor in American opposition to immigration in the 1920s, it wasn't the only reason.  Economic fears, isolationism, concerns about crime, and the sheer number of immigrants all played a part.  These elements interacted with each other, creating a complex web of reasons why many Americans wanted to limit immigration.  Understanding this interplay of factors helps explain why opposition to immigration was so strong during this time.