The Forest of Time
The Forest of Time is an alternate history novella by science-fiction writer Michael Flynn. It was originally published in the June 1987 issue of Analog magazine. In 1988, the story was nominated for the Hugo Award for Best Novella.
The story is set in an alternative world wherein the Thirteen Colonies, after gaining independence from Britain, did not succeed in creating the United States, but instead developed into separate and mutually hostile nation-states which often fight bitter wars with each other.
In the novella, the citizens of Pennsylvania speak a language they call "Pennsylvanisch," which a character describes as "[a] German dialect mainly derived from Swabian and with many English loan words, which a speaker of High German would find it difficult to follow".
This language has a rich literary tradition of which the Pennsylvanians are proud; and they feel suspicious of, and threatened by the hostile English-speaking nations of New York to their north, and Virginia to their south.
In that Pennsylvania, only the Quaker communities still speak English as their native language, and they are therefore recruited by the Pennsylvanian Intelligence Service as spies to infiltrate the territories of neighboring nations.
In actual US history, a large part of Pennsylvania's population in the 18th century were indeed German-speakers, though the elites in the colony and later state were English-speaking. The numbers of German speakers dwindled in later periods, though the language still survives, especially among the Amish. It is known as "Pennsylvania Dutch" ("Dutch" here meaning "German" rather than referring to the Netherlands) and sometimes also called "Pennsylvanisch" by its own speakers.
Flynn assumes that in a situation where Pennsylvania became an independent nation-state, distinct from and often fighting with its neighbors, Pennsylvanisch would have had a chance to become the official and dominant language, which later immigrants would learn upon arrival.