"As Maine goes, so goes the nation" was once a maxim in United States politics. The phrase described Maine's reputation as a bellwether state for presidential elections. Maine's September election of a governor predicted the party outcome of the November presidential election in 21 out of the 28 presidential election years from 1820 to 1932: namely 1820–1844, 1852 (albeit overturned in a run-off in the state legislature), 1860–1876, 1888, 1896–1908 and 1920–1928; more importantly, as Maine was a generally Republican-leaning state, the margin of the September elections compared to expectations could predict national November results more than the identity of the winning party in Maine. A contest still won by the Republicans but with a narrower margin than usual would still predict good Democratic results nationally.
Maine's reputation as a bellwether began in 1840, when it elected Edward Kent, the Whig Party candidate, as its governor; two months later, the Whig Party presidential candidate, William Henry Harrison, won the 1840 presidential election. Again in 1888, Maine voted solidly for Republican Party candidates, and Republican Benjamin Harrison won the presidential election despite losing the overall popular vote nationwide. The saying originated following this election, though it is unknown by whom.
