Old Monroe is a city in Lincoln County, Missouri, United States.

[5] The name was prefixed with "Old" in order to avoid postal conflict with Monroe City.

[6] The Battle of the Sink Hole was fought on May 24, 1815, after the official end of the War of 1812, between Missouri Rangers and Sauk Indians led by Black Hawk.

The Sauk were unaware, or did not care, that their British patrons had signed the Treaty of Ghent with the U.S.

The battle was fought in a low spot near the mouth of the Cuivre River near the current day city of Old Monroe.

After the battle, in 1816, Black Hawk reaffirmed the Treaty of St. Louis after re-negotiation with the United States government.

[7] The city was originally named "Monroe" and it served as the county seat from 1819 until 1823.

None of the families and 4.5% of the population were living below the poverty line, including no under eighteens and 5.6% of those over 64.