Peter J. McArdle (1874-1940) also known as P.J. McArdle was a labor activist and local politician in Pittsburgh.
Born in Belpre, Ohio and growing up in Muncie, Indiana, McCardle had moved to Western Pennsylvania no later than 1905. He was a rolling mill worker and union council member influential in Amalgamated Association of Iron and Steel Workers (hosting the 1909 convention) and the Steel strike of 1919.McArdle was elected to Pittsburgh City Council in 1911 with a source recording him in office for over 27 years. He was a member of the City Planning Commission when the Mt. Washington Roadway was proposed in 1912.McArdle's home in later life was on Bigham Street in the Mt. Washington neighborhood of Pittsburgh.
His son Joseph A. McArdle became a City Council member and Pennsylvania congressman.
McArdle ran in the 1933 Republican primary for Pittsburgh mayor.