A Republican, she served as a member of the Missouri House of Representatives from the 49th District in Callaway County and as a member of the Missouri Senate from the 10th District which includes the counties of Audrain, Callaway, Lincoln, Monroe, Montgomery and Warren.

Riddle is a 1972 graduate of McCluer High School in Florissant, Missouri.

Following college, she worked briefly in St. Louis in the accounting department of Southwestern Bell Telephone Company.

[3] In 2010, she was elected by her fellow caucus members to serve as the Assistant Majority Floor Leader through 2012.

[4] In her first term, Riddle served as vice-chair of the Public Safety committee as well as a member of the Tax Reform, Energy and Environment committees, also the Appropriations-Public Safety and Corrections subcommittee.