Capps first took office in 1998, succeeding her husband, Rep. Walter Capps, after he passed away less than one year into his term.
And there's a possibility the seat may stay in the family: Capps' daughter is Laura Burton Capps, a well-known Democratic political operative who is widely expected to make a competitive bid for the seat. Burton Capps -- who is married to Bill Burton, a former aide to President Obama -- has not publicly commented on her future plans but has been very active in the district. She and her husband relocated to Santa Barbara two years ago.
Capps' announcement also creates an enticing opening for potential Republican candidates. The National Republican Congressional Committee on Wednesday indicated it could become a target for the GOP.
“The 24th District has been competitive for multiple cycles and instantly becomes a more likely pick up opportunity for Republicans in 2016 with Lois Capps’ retirement," said NRCC spokesperson Zach Hunter.