[2] The county was officially organized on February 25, 1845, and was named in honor of former Governor of Missouri Thomas Reynolds.

Among the major first ancestries reported in Reynolds County were 37.6% American, 12.1% Irish, 11.6% German, and 11.4% English.

Reynolds County is divided into two legislative districts in the Missouri House of Representatives, both of which are held by Republicans.

All of Reynolds County is a part of the 3rd District in the Missouri Senate and is currently represented by Gary Romine (R-Farmington).

Smith won a special election on Tuesday, June 4, 2013, to finish out the remaining term of U.S. Representative Jo Ann Emerson (R-Cape Girardeau).

Emerson announced her resignation a month after being reelected with over 70 percent of the vote in the district.

[14] In 2000, George W. Bush carried the county for the Republican Party for only the third time ever, despite his narrow national popular vote defeat that year.

Like most rural areas throughout Southeast Missouri, voters in Reynolds County generally adhere to socially and culturally conservative principles but are more moderate or populist on economic issues, typical of the Dixiecrat philosophy.

The proposition strongly passed every single county in Missouri with 75.94 percent voting in favor as the minimum wage was increased to $6.50 an hour in the state.

During the same election, voters in five other states also strongly approved increases in the minimum wage.

In the 2008 presidential primary, voters in Reynolds County from both political parties supported candidates who finished in second place in the state at large and nationally.

Senator Hillary Clinton (D-New York) received more votes, a total of 741, than any candidate from either party in Reynolds County during the 2008 presidential primary.