Juniata County is a county located in the U.S. state of Pennsylvania. At the 2010 census, the population was 24,636. Its county seat is Mifflintown. The county was created on March 2, 1831, from part of Mifflin County and named for the Juniata River.
Mountains in Juniata County include Tuscarora Mountain and Shade Mountain. Agricultural land and forested land make up most of the county's area. Major rivers and creeks in the county include the Susquehanna River, the Juniata River, Tuscarora Creek, and West Branch Mahantango Creek. It borders six other counties. The county lies over 16 different rock formations (which are from the Ordovician, Silurian, and Devonian) and 51 different soils.
Juniata County has a relatively low population density. The most population-dense parts of the county are the boroughs of Mifflintown and Mifflin. The most common races in the county are white (96.8% of all residents) and black (0.6% of all residents). Between 1940 and 2005, Juniata County's population grew faster than all but two other counties in Pennsylvania. Susquehanna Township had the fastest-growing population of any borough or township in the county during this time period. Livestock farming is the largest industry in the county, although there are other industries as well, including crop farming and tourism. Manufacturing jobs are the most common jobs in the county. The county's median household income is $34,698 per year and its median family income is $39,757 per year. The poverty rate is 9.5% and the unemployment rate is 5.4%. The median house value in the county was $87,000 in 2000. The main roads in Juniata County are Pennsylvania Route 235, Pennsylvania Route 35, Pennsylvania Route 104, U.S. Route 11/U.S. Route 15, U.S. Route 22/U.S. Route 322, Pennsylvania Route 74, Pennsylvania Route 850, and Pennsylvania Route 333.
There are four boroughs and thirteen townships in Juniata County. The county is served by two school districts: the Juniata County School District and the Greenwood School District. There are five areas in Juniata County that are protected by the Central Pennsylvania Conservancy and 59 natural heritage sites in the county.
The first settlers arrived in Juniata County in the 1750s. The county has historically been part of Mifflin County and before that, part of Cumberland County.