It’s a good point, but it’s widely used throughout Germany and it was the German settlers that brought it from the coast across most of the Midwest.

-burg does have distant Dutch origins and is used in some Dutch names, but it’s also pervasively used across Germany more than the Dutch use it.

German city names: Hamburg, Strasburg, duiesburg, Ludwigsburg, wurzburg, coburg, Marburg, Wolfsburg, brandenburg, flensburg, Oldenburg, oranienburg, You also get a wide variety of -berg in Germany.

Other common German suffixes are -heim, -feld, -hausen, -stadt, -haven. These are less common in America, but can happen on occassion.

There is a Oostburg Wisconsin and that is a very, very Dutch name and that area was settled by the Dutch. Most of the earlier Dutch settlements were in NY and NJ along the coasts and they don’t frequently use -burg, but there is a decent amount of -berg and berg- that could likely be attributed to the Dutch over Germany.