Penn Township is one of twelve townships in Jay County, Indiana, USA. As of the 2000 census, its population was 1,308.Penn Township covers an area of 30.17 square miles (78.1 km2); of this, 0.02 square miles (0.052 km2) or 0.05 percent is water. The streams of Brooks Creek and Haines Creek run through this township. Jay County was formed in 1836. It is the only county in the United States named for John Jay, co-author of the Federalist Papers, Secretary of Foreign Affairs under the Articles of Confederation, and first Chief Justice of the United States. John Jay died in 1829.