Jernigan served a four-year stint in the United States Air Force, then earned a B.S.
He moved to Ann Arbor in the early 1970s to work as an investment officer at the University of Michigan, where he remained employed until his retirement in 2001.
Jernigan won reelection as mayor in 1989, beating back a challenge from Democratic candidate Raymond F. Clevenger, who had served as a U.S. Representative from Michigan's 11th district from 1965-67.
In November 2002, Jernigan was elected to a six-year term on the Board of Trustees for Washtenaw Community College.
On July 18, 2006, Jernigan died at his home in Ann Arbor, after playing a round of golf.