[6] Mercer County is one of the 423 counties served by the Appalachian Regional Commission,[7] and it is identified as part of the "Midlands" by Colin Woodard in his book American Nations: A History of the Eleven Rival Regional Cultures of North America.

37.7% were of German, 20.0% Irish, 14.9% Italian, 12.0% English, 6.4% American, 6.2% Polish, 3.7% Scotch-Irish, 3.3% Dutch ancestry.

[19] Chart of Voter Registration Mercer County was previously considered a political bellwether for the state of Pennsylvania since its demographics, urban-rural ratio, and party affiliation once closely mirrored the state as a whole.

This trend failed to hold true in 2004 and 2008, in which Mercer County voted more conservatively than the rest of the state.

Each of the three Republican candidates for statewide office carried Mercer County in 2016.

In 2020, Trump again carried the county, despite Pennsylvania narrowly voting for Joe Biden.

[citation needed] There is one Pennsylvania state park in Mercer County.

Maurice K. Goddard State Park, named for Maurice K. Goddard, former Secretary of the Pennsylvania Department of Environmental Resources, is just off exit 130 of Interstate 79 on Pennsylvania Route 358 near Stoneboro.

Under Pennsylvania law, there are four types of incorporated municipalities: cities, boroughs, townships, and, in one case, towns.