According to Wikipedia, there were 425,000 German prisoners of war housed in 700 camps throughout the United States during World War II. I had no clue…….. until the fact was mentioned in a genealogy program. The map below is fuzzy but you get the idea.

After the U.S. entered World War II in 1941, the British Government requested American help with housing prisoners of war due to a housing shortage in Britain. The U.S. was asked to take 175,000, and reluctantly agreed since we were not prepared to house and care for them. As the war years slipped by, sometimes as many as 30,000 prisoners per month arrived into New York or Virginia where they were processed and distributed to camps. Some 46 of the 48 states hosted camps. 

After the war, the German prisoners were expected to go home immediately, but seeing that their treatment had been good, some 5000 Germans emigrated back to the U.S. Some stayed in other European countries. A national poll found that 74% of Americans solely blamed the German government for the war, not Germans. 

The camps in the U.S. are otherwise what the Associated Press later called an “all but forgotten part of history.” About 860 German POWs remain buried in 43 sites across the U.S. In some local communities which formerly hosted POW camps, local residents often do not know the camps ever existed. 
Washington had two camps:  Fort Lewis and Fort Lawton.  Idaho had two:  Farragut and Camp Rupert.  Oregon had two:  Camp White and Camp Warner.  Montana never had a POW camp. 

If you’d like to know more, Wikipedia has a 13-page article on German Prisoners of War in the United States.