Mercer County Airport (IATA: BLF, ICAO: KBLF, FAA LID: BLF) is in Mercer County,[1] three miles northeast of Bluefield, West Virginia[1] 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.

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).

Mercer County Airport covers 511 acres (207 ha) at an elevation of 2,857 feet (871 m).

[1] In the year ending July 11, 2023, the airport had 16,400 aircraft operations, average 45 per day: 88% general aviation, 11% air taxi, and <1% military.