Industrial development in the northwestern portion of St. Louis is primarily due to the St. Louis Terminal Railroad (now Terminal Railroad Association), which began to acquire right-of-way through the area in 1892. After the laying of track was completed in 1900, availability of rail access along with the vast area of vacant land attracted many new industries. This belt line connects the railroads along the river in the Hall Street section with lines in St. Louis County.
Public transit reached the Walnut Park area in 1893, when the Bellefontaine branch of the Union Depot Railroad Company was extended out Florissant Avenue from Grand to Calvary Avenue. This new electric line was intended to serve visitors to the cemeteries. About that time, the St. Louis and Suburban Railway placed in service an extension running north on Union from Forest Park to Florissant Avenue. The Florissant Avenue Electric Railway Company then built a line west on Florissant from Calvary Avenue to Robin Avenue. After the transit consolidation of 1899 and the merger of the Suburban line with the consolidated United Railways in 1907, these lines came under control of that company. The Florissant Avenue line was added to the Bellefontaine line, looping at Robin Avenue.
About 1911, a locally owned trolley line began operations on Florissant Avenue westward from the loop at Robin Avenue to Jennings Station Road and later ran a branch on Helen Avenue from Florissant to Lilian. It was called the "Dinky" because of the small size of its cars. Lack of business forced the line into bankruptcy in 1925. Soon after that the St. Louis Bus Company, operated by the United Railways, began a bus line from the loop to Jennings and also south on Helen Avenue and Jennings Station Road to Natural Bridge. In 1924, the Peoples Motorbus Company inaugurated its Walnut Park line providing direct service downtown. It looped at Riverview and Thekla and ran eastwardly through the area to Kingshighway and thence eastward on Florissant Avenue. This company was absorbed later by the United Railways. By 1947, streetcar lines in the area were converted to bus operation by the St. Louis Public Service Company.
Through traffic in the area uses West Florissant, Union, Kingshighway, Riverview and the Mark Twain Expressway (Interstate 70). The route for I-70 was chosen in the early 1950's, with final surveying beginning in 1955. Demolition for its right-of-way took about 200 houses and five businesses from Walnut Park. Some houses were removed to other sites after being sold at auction. Clearance for the highway began in 1956 and construction started two years later; Mark Twain Expressway was opened in June 1961, and soon found its traffic volume design capacity exceeded. It provides a convenient link for Walnut Park with both downtown and Lambert Airport.