I've had Kevin Boyle's telling of a 1925 race-related murder and aftermath, Arc of Justice, on my shelf for a few months and finally picked it up. I find the paragraph below in the prologue of the book:
"The nativists campaign reached high tide in 1924. Anti-immigrant groups had been demanding for years that Congress restrict entry into the United States. The pressure became intense in the early 1920s. Veterans groups lobbied their representatives, the Klan launched a massive letter-writing campaign, businessmen endorsed restriction, and nativist scientists and authors appeared before congressional committees to explain the growing threat to the American racial stock. Congress finally surrendered in the spring of 1924. The National Origins Act imposed such strict limits on the number of immigrants allowed into the country that, for all intents and purposes, it ended the great era of immigration, now eight decades old. Ethnic spokesmen pleaded with the president to veto the bill. But (Calvin) Coolidge remained silent, as was his habit."
How far we've come in 80+ years. How very far.