Select the way you want to see the data shown. Then, click on any county to see data about its Pennsylvania German population.
The name Pennsylvania Germans, also called "Pennsylvania Dutch" in some parts of the state, primarily refers to German Protestant immigrants who entered Pennsylvania in the 1700s and 1800s. Many were members of two well-known sects, the Amish and the Mennonites. A large proportion of these Pennsylvania Germans held to rural livelihoods.
The Pennsylvania Germans first immigrated several decades after the earliest English colonists gained possession or control over most land in Philadelphia and its first ring of surrounding counties. The most accessible area for the Germans, then, was the second ring of counties, from Northampton County to Lancaster County. From there they continued to filter into the third ring, where they intermingled with Scotch-Irish immigrants.
Philadelphia and its suburbs grew rapidly, especially in the later 1800s and continuing up to shortly after World War II. That growth all but eliminated Pennsylvania Germans from the first ring of Philadelphia suburbs, and increased the sizes of urban settlements in the second ring counties they originally settled. While many of the German immigrant families continued to farm, and to own large amounts of land, their proportion of the population shrank because the towns and cities had so many more inhabitants.
Those facts show up clearly in these two maps. In terms of the numbers of Pennsylvania Germans, the Northampton to Lancaster (second) ring still dominates because this is the region with the best agricultural soil in the state. In terms of the proportion of Pennsylvania Germans, the third ring of counties dominates. These counties attracted fewer original Germans but never grew such large urban populations, so the proportion of Pennsylvania Germans was not as diluted. Of course, if you look at the numbers and percentages on these maps, they are not large. But in the context of this one culture, the differences are intriguing.