Moved to Iowa, 1836; elected to legislative assembly Iowa Territory, 1838, 43, 68, became chairman judiciary committee. Leader in promoting railroads for Iowa. Charter member Southern Iowa Horticultural Society.
Governor Iowa (Whig), 1854-1858. His administration established state university at Iowa City. A founder of Republican Party in Iowa.
Member United States Senate (Republican) from Iowa, 1859-1869. Carried into Senate chamber (because of paralytic stroke) during voting at impeachment trial of Andrew Johnson, voted not guilty (which resulted in Johnson’s acquittal). His political reputation and leadership suffered as result of this action.
Instrumental in keeping Naval Academy at Annapolis.