Mercer County is now the 8th county that comprises the Pittsburgh Metropolitan area.
The U.S. office of Management and Budget changed its definitions of Core Based Statistical Areas (CBSA) across the United States. Previously, Mercer County was a micropolitan statistical area but when updates standards they have now been added to the Pittsburgh Metropolitan area.
In 1993 Butler was added to the Pittsburgh Metropolitan area but most recently Armstrong County in 2003. The Pittsburgh Metropolitan area now includes Lawrence, Beaver, Washington, Fayette, Westmoreland, Indiana, Armstrong, Butler, and Allegheny.
