[1] The district encompasses a portion of the city's central business district, whose historical significance extends from about 1885 to the end of World War II.

[2] The original 1988 boundary of the district included buildings on two blocks of Walnut Street, between Second and Arkansas Streets, and encompasses a cluster of predominantly commercial buildings built between 1885 and 1912.

In 1993 the district was enlarged to include two blocks of First and Second Streets, between Walnut and Poplar Streets, which also included historically significant commercial buildings constructed up to 1943.

This enlargement included the previously-listed Old Post Office, Lane Hotel, Applegate Drugstore, and Bank of Rogers Building.

In 2012 it was enlarged yet again, adding the 200 block of West Elm Street.