Hollidaysburg is a borough in and the county seat of Blair County in the U.S. state of Pennsylvania. It is located on the Juniata River, 5 miles (8 km) south of Altoona and is part of the Altoona, Pennsylvania, Metropolitan Statistical Area. In 1900, 2,998 people lived in the borough, in 1910, 3,734 lived there, and in 1940, 5,910 residents were counted. The population was 5,791 at the 2010 census. Coal, iron ore, ganister, and limestone are found in the vicinity. In the past, the borough had foundries and machine shops, a silk mill, car works and classification yards.
From 1834 to 1854, the borough was an important port on Pennsylvania Main Line Canal, where the Juniata Division Canal connected to the Allegheny Portage Railroad.
The center of Hollidaysburg is frequently referred to as "The Diamond," where the buildings and parking spaces form a diamond. This area serves as the hub for parades, festivals and other town celebrations.
The borough of Hollidaysburg was first laid out in 1796 and was named after Adam and William Holliday, Irish immigrants who founded the settlement; by 1814 it consisted of several houses and a tavern.