[a] Blair County comprises the Altoona, PA metropolitan statistical area.

It is also part of the Altoona-Huntingdon, PA Combined Statistical Area, which includes Blair and Huntingdon counties.

[5] Blair County is one of the 423 counties served by the Appalachian Regional Commission,[6] and it is identified as part of "Greater Appalachia" by Colin Woodard in his book American Nations: A History of the Eleven Rival Regional Cultures of North America.

Franklin D. Roosevelt in 1936 and Lyndon B. Johnson in 1964 are the only Democratic presidential candidates to date to win the county (with neither taking more than 52% of the county's vote), although Theodore Roosevelt won it as the candidate of the Progressive Party in 1912.

Under Pennsylvania law, there are four types of incorporated municipalities: cities, boroughs, townships, and, in at most two cases, towns.

The following cities, boroughs and townships are located in Blair County: Census-designated places are geographical areas designated by the U.S. Census Bureau for the purposes of compiling demographic data.