115 continues north through a rural area, passing the unincorporated community of Middlebrook before crossing the Missouri state line, where it continues as Missouri Route 21. The ARDOT maintains Highway 115 like all other parts of the state highway system. As a part of these responsibilities, the Department tracks the volume of traffic using its roads in surveys using a metric called average annual daily traffic (AADT). ARDOT estimates the traffic level for a segment of roadway for any average day of the year in these surveys. As of 2018, the peak AADT on the highway was 5,000 vehicles per day (VPD) near Pocahontas, dropping to 800 VPD near the Missouri border. The AADT was under 2000 between Cave City and Imboden. No segment of Highway 115 has been listed as part of the National Highway System, a network of roads important to the nation's economy, defense, and mobility. History During the 1926 Arkansas state highway numbering, a route similar to the present alignment of Highway 115 was created between Cave City and Missouri as State Road 79. By September 1928, State Road 79 was rerouted between Imboden and Smithville along a more direct route, with the former alignment becoming Highway 117. When US 62 was designated across Arkansas in 1931, it replaced State Road 79 between Imboden and Pocahontas. When US 79 was designated across Arkansas in 1935, the State Road 79 designation was changed to State Road 115 to avoid duplication. State Road 115, which had been an original state highway between El Dorado and Thornton in South Arkansas, was supplanted by US 167, which had been relocated as part of the US 79 designation. Major intersections See also List of state highways in Arkansas Notes References External links 115 Transportation in Sharp County, Arkansas Transportation in Lawrence County, Arkansas Transportation in Randolph County, Arkansas U.S. Route 62