Mark Brandt Dayton (born January 26, 1947) is an American politician who served as the 40th governor of Minnesota from 2011 to 2019. He served as a United States Senator representing Minnesota from 2001 to 2007 and as Minnesota State Auditor from 1991 to 1995. He is a member of the Minnesota Democratic–Farmer–Labor Party (DFL), which affiliates with the national Democratic Party. A native of Minnesota, Dayton is the great-grandson of businessman George Dayton, the founder of Dayton's, a department store that later became the Target Corporation. He embarked on a career in teaching and social work in New York City and Boston after graduating from Yale University in 1969. During the 1970s, he served as a legislative aide to U.S. Senator Walter Mondale and Minnesota Governor Rudy Perpich. In 1978, Dayton was appointed the Minnesota Economic Development Commissioner and married Alida Rockefeller Messinger, a member of the Rockefeller family.Dayton ran for the U.S. Senate in 1982 against Republican Party incumbent David Durenberger. He defeated former U.S. senator Eugene McCarthy in the Democratic primary, and the general election became one of the most expensive in state history. Dayton campaigned as a populist in opposition to Reaganomics and famously promised "to close tax loopholes for the rich and the corporations—and if you think that includes the Daytons, you're right." Durenberger won the election, and Dayton returned to the Perpich administration until his election as Minnesota State Auditor in 1990.In 1998, Dayton ran for governor, losing the Democratic nomination to Hubert Humphrey III. In 2000, he was elected to the U.S. Senate, defeating Republican incumbent Rod Grams. As senator, Dayton voted against the authorization for Iraq War, and became the first senator to introduce legislation creating a cabinet-level United States Department of Peace. In 2006, he chose not to seek reelection, citing his disillusionment with Washington, D.C., and fundraising.In 2010, Dayton defeated Republican Tom Emmer to become governor of Minnesota despite national success for the Republican Party, including in the Minnesota legislature. He won a second term in 2014 over Republican opponent Jeff Johnson and opted not to run for a third term in 2018. His major legislative initiatives during his governorship include the legalization of same-sex marriage and the construction of U.S. Bank Stadium.