From the
About.com
article: "German the Official US Language? - Did German lose out to English by just one vote?":
Quote:[...]
Any claim that German might have become the main language of Pennsylvania in the 1790s, when over 66 percent of the population spoke English, is absurd.
The legend's Pennsylvania Connection
The German-as-official-language vote legend got its start in Pennsylvania. There actually was a vote on German in that state in the 1790s, but the facts are very different from the legend.
The vote and the legend are sometimes given the name "Muhlenberg," after the Speaker of the House, Frederick Augustus Conrad Muhlenberg (1750-1801) of Pennsylvania. The German Lutheran Muhlenberg (a descendent of Henry Melchior Mühlenberg, who left Germany for Pennsylvania in 1742), despite his background apparently spoke little German himself, and favored English as the language of education and religion. According to the Muhlenberg legend, Muhlenberg stepped down as Speaker to cast the negative vote that deprived German of its official status in America. But, of course, the facts differ substantially from the legend, and the man who contributed the most to this garbling of history was also German. Franz Löher published "History and Achievements of the Germans in America" in 1847. In his work, Löher put the blame on Muhlenberg for the failure of German to become the official language, not of the US, but of the state of Pennsylvania. Later, others would warp Löher's version into a legend concerning the entire United States.
While the German vote legend may be fiction, the historical influence of Germans in Pennsylvania and the US should not be underestimated. The first Germans crossed the Atlantic aboard a ship named the Concorde in 1683. The community they established, Germantown, is today part of Philadelphia. The German Society of Pennsylvania was established in 1764 and is still functioning today from its headquarters in Philadelphia.
Even the German Society of Pennsylvania
doesn't mention it.
You should find more at [researched via the internet/library services]:
Feer, Robert A. : Official use of the German language in Pennsylvania. Pennsylvania Magazine of History and Biography no. 76 (1952), page 394-405.