Altoona is a city in Blair County, Pennsylvania, United States. The population was 43,963 at the time of the 2020 census. It is the principal city of the Altoona metropolitan area, which includes all of Blair County and was recorded as having a population of 122,822 in 2020. Altoona was established in 1849 by the Pennsylvania Railroad. Having grown around the railroad industry, the city has worked to recover from industrial decline and urban decentralization experienced in recent decades.