Mercer County Airport (IATA: BLF, ICAO: KBLF, FAA LID: BLF) is in Mercer County, three miles northeast of Bluefield, West Virginia and about nine miles southwest of Princeton, West Virginia. The National Plan of Integrated Airport Systems for 2011–2015 categorized it as a general aviation facility.

The airport has been served by scheduled airlines. Service was subsidized by the Essential Air Service program until August 1, 2006, when it ended due to federal law not allowing a subsidy over $200 per passenger for communities within 210 miles of a large or medium hub airport (Charlotte/Douglas International Airport in North Carolina being 173 miles away). Federal Aviation Administration records say Mercer County Airport had 2,041 passenger boardings (enplanements) in calendar year 2004, 1,885 enplanments in 2005, 1,833 in 2006 and 1,721 in 2007. Scheduled passenger flights ended in 2007.