In 1966, Blackburn was elected as a Republican to the Ninetieth Congress, having narrowly defeated freshman incumbent James MacKay by 360 votes: 55,249 (50.2 percent) to 54,889 (49.8 percent). In that same election fellow Republican Bo Callaway challenged the Democrat Lester Maddox, a strong segregationist from Atlanta, in the 1966 gubernatorial race.
Blackburn was elected as a Republican to the Ninetieth Congress in 1966 after narrowly defeating James MacKay by 360 votes. At the same time, fellow Republican Bo Callaway challenged Democrat Lester Maddox, a prominent segregationist from Atlanta, in the 1966 gubernatorial contest.