People mention the world wars and repression of German--but these things merely accelerated a process that would have happened anyway unless there were new immigrants to make up for the assimilation of the older ones. To quote an old post of mine:
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In 1893-4 there were almost 800 German-language publications in the US. "With the decline of immigration and the consolidation trends after 1890, German-language publications declined to 613 in 1900 and 554 in 1910...*World War I accelerated an ongoing decline.* [my emphasis--DT] *Harvard Encyclopedia of American Ethnic Groups,* p. 420 (article "Germans")
The main reason German was a flourishing language in the US in the early twentieth century was simply that there were so many fairly recent German immigrants. As late as 1890 Germans represented 30.1 percent of the foreign-born in the US--that went down to 25.8 percent in 1900 and 17.1 percent in 1910 and then to 12.1 percent in 1920--that last figure being only in part a result of the War. With the decline of German immigration, the German language was likely to decline. This happened with other languages, too. "In 1923, when the Polish-American journals were at their height, at least 19 dailies, 67 weeklies and 18 monthlies were in circulation." *Harvard Encyclopedia of American Ethnic Groups,* p. 800 (article "Poles") After 1930, "the number of the Polish press titles...began to decline steadily."
https://books.google.com/books?id=Jyd_DAAAQBAJ&pg=PA202 Yet the US had never gone to war with Poland...
Again, I am not denying that the world wars encouraged German-American assimilation--but they only accelerated a trend that would have taken place anyway.
https://www.alternatehistory.com/fo...cuisine-in-the-us.415902/page-2#post-14738637