McClain began her career at AmSouth Bank in 1980 while she was attending Jefferson State Community College. She completed her bachelor's degree in accounting in 1984 at UAB, and remained with AmSouth until 1995, when she left to take a job with MedPartners. In 2000 she was hired by the city of Brighton, leaving in 2007 for a position with the American Trust Corporation. In 2009 she joined the staff of the Jefferson County Commission as director of community affairs.
McClain challenged 8-term incumbent Dorris Britton in the 2012 Democratic primary and defeated former Jefferson County Commissioner Bobby Humphryes in the 2012 general election. She defeated Republican challenger Brandon Herren in the 2016 general election to retain her office.
- Chambers, Jesse (November 6, 2012) "Democratic women win two races in Bessemer Cutoff." The Birmingham News