How the Iowa caucuses shape history
Iowa has been the first state in the nation to hold a nominating contest since 1972, and since then all but three of the eventual Democratic nominees have come out on top in Iowa. CBS News' Sarah Ewall-Wice reports on the history, while Elaine Quijano anchors from Des Moines with CBSN contributors Leslie Sanchez, Lynda Tran and Antjuan Seawright.