Editing Caesar Augustus Rodney (section)

==Later political activity==
Rodney returned to politics, serving in the [[Delaware State Senate]] for three sessions from 1815 through 1817. In 1820 he was again elected to the U.S. House, serving from March 4, 1821, until January 24, 1822, when he resigned upon being elected to the U.S. Senate. He served there only a year as well, resigning January 29, 1823, to accept a diplomatic appointment. During that brief year Rodney was Delaware's only Democratic-Republican U.S. Senator ever.

Along with [[John Graham (diplomat)|John Graham]] and [[Theodorick Bland (judge)|Theodorick Bland]], Rodney was selected by President [[James Monroe]] in 1817 for a special diplomatic mission to [[South America]], the [[South American Commission of 1817–1818]].<ref name="Rasmussen">{{cite book |last1=Rasmussen |first1=Wayne D. |editor1-first=James |editor1-last=Gerber |editor2-last=Lei Guang |title=Agriculture and Rural Connections in the Pacific, 1500–1900 |url=https://books.google.com/books?id=E1d5L9tXXq0C |series=The Pacific World: Lands, Peoples and History of the Pacific, 1500–1900 |volume=13 |year=2006 |publisher=Ashgate Publishing Company |location=Burlington, Vermont |isbn=978-0-7546-3978-7 |pages=53–62 |chapter=Diplomats and Plant Collectors: The South American Commission, 1817–1818 |chapter-url=https://books.google.com/books?id=E1d5L9tXXq0C&pg=PA53 }}</ref> Rodney was appointed to lead the commission to investigate whether the newly formed [[South America]]n republics should be recognized. He strongly advocated such recognition and, with Graham, published his findings in 1819 as ''Reports on the Present State of the United Provinces of South America.'' This report is thought to have contributed much to the thinking behind the policy that eventually became expressed as the [[Monroe Doctrine]]. It also resulted in Rodney's 1823 appointment as United States [[Minister (diplomacy)|Minister Plenipotentiary]] to the [[United Provinces of the Río de la Plata]], now known as Argentina. He remained at this posting until his death.