Monaca (/mɨˈnækə/ mi-nak-ə) is a borough in Beaver County, Pennsylvania, United States along the Ohio River, 25 miles (40 km) northwest of Pittsburgh. Monaca was first incorporated as Phillipsburg in 1840, and had been known by that name since the 1820s. In 1892, the name of the borough was changed to Monaca in honor of the Native American Indian Monacatootha. Monacatootha (which means “Great Arrow”), also known as Scarouady, was an Oneida warrior chief, and was a representative of the Iroquois Confederacy with the authority to supervise affairs among the Delawares and Shawnees in that area. He met with George Washington in Logstown in 1753. He was a strong friend of the English and campaigned against the French. Monaca Borough took its name from a Pittsburgh and Lake Erie Railroad station at the east end of town. Fire clay is found in large quantities in the vicinity. In 1900, the population was 2,008; in 1910, 3,376; and in 1940, 7,061 people were residents. The population was 6,286 at the 2000 census.
Monaca is located at 40°41′2″N 80°16′37″W (40.683966, -80.276986).
According to the United States Census Bureau, the borough has a total area of 2.5 square miles (6.5 km2), of which, 2.1 square miles (5.4 km2) of it is land and 0.4 square miles (1.0 km2) of it (16.40%) is water.