These are mainly elderly, and are found in all parts of the country.
It would seem that from 22 to 24% of the non-Hispanic WHITE population of the USA are German surnamed, or were before anglicizing that often occurred in the 18th and 19th centuries, such as Klein to Cline, Steinbrenner to Stoneburner, Kreisler to Chrysler, etc.
Much of this immigration was from areas no longer under German control, however, and over 80% of it was non-Catholic...much of it was non-Lutheran also, because America served as a refuge for minority religious groups viewed as cults in Germany, such as Baptists, Calvinist and Reformed groups, Mennonites, etc.
Many of these were from areas now included in Czechoslovakia or Poland.
At one time, Wisconsin had dual German and English school systems, and some feared that State would remain German speaking forever.
German immigration peaked in the 1740-80 era, and again in the 1840-80 era. The heyday of Ellis Island saw relatively few German speakers come in, though many non-German Catholic elements from the Austrian and German empires did come then.
It is a little-known fact that over 10% of the German-speaking heritage now in USA are descendents of displaced persons and other refugees accepted here AFTER World War II, in the 1945-60 era.
If Schroeder keeps running Germany in the hole, maybe more will yet come over, if they think they can compete with blacks and Mexicans for jobs, in the very teeth of affirmative-action's labeling them as whites, quien en los estados unidos comen cola.