The Republican Party totally dominated Pennsylvania politics from 1860, when the first Republican governor was elected, to the early 1930s. During this period, there were 16 Republican and only two Democratic administrations. Most of the Republicans were staunchly probusiness, though one Republican Progressive, Gifford Pinchot, was elected governor in 1922 and again in 1930. A Democrat, George Earle, won the governorship in 1934, in the depths of the Depression, but from 1939 through 1955, Republicans again held the office without interruption. Only since the mid-1950s has Pennsylvania emerged as a two-party state, with Democrats electing governors in 1954, 1958, 1970, 1974, 1986 and 1990, and Republicans winning the governorships in 1962, 1966, 1978, 1982, and 1994. In 1998, Tom Ridge, the Republican first elected to the office in 1994, won a second term as governor. He was named the first secretary of the newly-created Department of Homeland Security in November 2002, after having served as the first administrator of the Office of Homeland Security from September 2001. In 2002, Democrat Ed Rendell was elected governor.
Both US Senate seats were held by Republicans from 1968 to 1991. In November of 1991, a little-known Democrat and former college president named Harris Wofford defeated former governor Richard Thornburgh for the seat of Senator John Heinz, who died in 1991. In 1994, Republican Rick Santorum, a congressman from the Pittsburgh area, defeated Wofford; Santorum was reelected in 2000. Pennsylvania's other senator, Republican Arlen Specter, was elected to his fourth term in 1998. In 2003, Pennsylvania's 19 US House seats were held by seven Democrats and 12 Republicans. In mid-2003, there were 29 Republicans and 21 Democrats in the state senate, and 109 Republicans and 94 Democrats in the state house.
Democratic voters were heavily concentrated in metropolitan Philadelphia and Pittsburgh. Pennsylvania, a pivotal state for Jimmy Carter in 1976, was swept by the Republican tide in the 1980 presidential election; Ronald Reagan, the Republican nominee, won nearly 50% of the popular vote. In 1984, President Reagan received 53% of the popular vote, while Democrat Walter Mondale received 46%. In 1988, Republican and former vice president George Bush won 51% of the popular vote. Democratic nominee Bill Clinton garnered 45% of the vote in 1992, and in 1996, Clinton won 49% of the vote. In 2000, Democrat Al Gore won 51% of the vote to Republican George W. Bush's 47%; Green Party candidate Ralph Nader won 2% of the vote. In 2002 there were 7,835,775 registered voters. In 1998, 48% of registered voters were Democratic, 42% Republican, and 9% unaffiliated or members of other parties. The state had 23 electoral votes in the 2000 presidential election.