Joseph M. McDade, an 18-term Republican congressman from northeastern Pennsylvania who helped revive the local coal-driven economy, and who late in his career was accused and acquitted of helping himself to $100,000 in illegal gifts, died on Sunday at his home in Fairfax, Va. He was 85.

His death was confirmed in a statement from his family. He had had Parkinson’s disease since the 1990s.

Elected in 1962 to succeed William W. Scranton, who ran successfully for governor that year, Mr. McDade retired at the end of 1998 as the longest-serving Republican in the House. He had the longest tenure of any Pennsylvania representative until 2010, when his record was surpassed by John P. Murtha just two days before Mr. Murtha died.

Conservative on social issues and an ardent advocate for military spending, Mr. McDade was immensely popular in his 10th Congressional District, in Lackawanna County, winning re-election even in the Democratic landslide of President Lyndon B. Johnson in 1964. He was a largely pro-labor Republican who delivered generous servings of pork barrel legislation to his constituents.