It’s a truism of politics here and everywhere that voters will tend to vote for people like themselves.
White people tend to vote for white politicians, black people tend to vote for black politicians, as do Hispanic-Americans, Irish-Americans, Italian-Americans, Cuban-Americans, and, probably in the current case, German-Americans.
Trump did not run explicitly as a German-American, and neither did our two previous German-American presidents (Hoover and Eisenhower). That’s no surprise, given our two 20th-century world wars against Germany.
But still, voters vote for people like them, and it is probably not a coincidence that Trump did very well in states with a substantial percentage of German-Americans.
More, below.