If Democratic attorney Conor Lamb upsets State Representative Rick Saccone in next Tuesday’s special election in Pennsylvania’s 18th Congressional District, it will mark just the second time a seat has flipped across 29 specials held in the Keystone State since 1951. Over the last 67 years, Democrat John Murtha’s February 1974 0.2-point win against Harry Fox is the only time a seat has changed partisan control in a Pennsylvania U.S. House special election. There have been some close calls with three other races decided by less than five points: April 1960, 17th CD (won by Republican Herman Schneebeli), April 1972, 27th CD (Republican William Conover), and April 1980, 11th CD (Democrat Raphael Musto). Four others have been decided by less than 10 points during this period: July 1963, 15th CD (Democrat Fred Rooney), July 1981, 3rd CD (Democrat Joseph Smith), May 2001, 9th CD (Republican Bill Shuster), and May 2010, 12th CD (Democrat Mark Critz). The average victory margin of 26.8 points during these previous 28 specials has been 6.1-points closer than the 32.9-point average during each district’s previous general election.