The only U. S. state to call its political subdivisions "parishes"?

Minnesota

Alaska

Pennsylvania

Louisiana

While Alaska calls it's subdivisions parishes, it is more common in the state of Louisiana.

The only US state to call its political subdivisions "parishes" is Louisiana.

Explanation:

Louisiana is one of the fifty states that, together with Washington D. C., form the United States of America. Its capital is Baton Rouge and its most populous city, New Orleans. It is located in the southern region of the country. It limits to the north with Arkansas, to the east with the Mississippi and Pearl rivers, which separate it from Mississippi, to the south with the Gulf of Mexico (Atlantic Ocean) and to the west with Texas (most of this border forms the Sabine River). It was admitted to the Union on April 30, 1812, as state number 18. Other important cities are Lafayette and Shreveport. Louisiana is the only state in the country whose political subdivisions are called parishes, which are local governments equivalent to the counties of the other states. The most populous parish is the parish of East Baton Rouge, and the largest by area is the parish of Plaquemines.