Marianna is a borough in Washington County, Pennsylvania, United States. The population was 626 at the 2000 census.
Marianna was built as a mining town for the Pittsburgh Buffalo Company in 1907 and was incorporated in 1910. Marianna is most famous for being the site of a mine explosion on November 30, 1908 which killed 154 making it the 10th deadliest mining disaster in U.S. history. After the disaster, the mine was sold to Bethlehem Steel who continued to extract coal until 1988, when the main conveyor caught fire. The fire was extinguished, but the mine closed anyway.
Marianna is located at 40°0′56″N 80°6′38″W / 40.01556°N 80.11056°W / 40.01556; -80.11056 (40.015626, -80.110483).