Mount Union is a borough in Huntingdon County, Pennsylvania, United States, approximately 44 miles southeast of Altoona and 12 miles southeast of Huntingdon, on the Juniata River. In the vicinity are found bituminous coal, ganister rock, fire clay, and some timber. A major Easter grass factory is located in the northern quadrant of the borough limits; until May 2007, the facility was owned by Bleyer Industries. The population was 2,447 at the 2010 census.