The existing junctions were also modified or replaced to meet later traffic needs and updated design standards, including the state's first single-point urban interchange.

It then crosses the Big Sioux River, which it follows through several city parks and interchanges that serve a commercial district along 41st Street and the Western Mall, another major shopping center.

[12][13] The plan was forwarded to the South Dakota Department of Highways for further development and to the federal Bureau of Public Roads (BPR), who endorsed the proposal in 1954.

[14] The BPR later included the bypass in their 1955 recommendation for urban routes that would form the national Interstate Highway System, which was approved by the U.S. Congress in 1956.

[20] This included a 198-foot-wide (60 m) strip near Logan Avenue in eastern Sioux Falls that had been acquired by the state government in 1949 with funds from the relocation of the South Dakota School for the Deaf.

[30] The completion of the freeway system around Sioux Falls led to residential and commercial development in the southwestern reaches of the city due to its proximity to I-29 and I-229.

[3]: 33–34  A pair of new interchanges—I-29 at West 26th Street and I-229 at Louise Avenue—were proposed in the 1980s to relieve traffic congestion at the Western Avenue interchange, which provided the main access to the retail area.

[28][35] An additional interchange was proposed at Benson Road in northeastern Sioux Falls in the 1980s to serve planned industrial parks in the area and was formally approved by the state government in 1989.

[36] It was scheduled to be completed in November 1991, but was delayed due to construction issues; the ramps were barricaded over the winter months, but were moved by motorists who used the unfinished interchange as a shortcut.

[37] The interchange opened in 1992 and was the first in eastern South Dakota to have planted wildflower patches to beautify the area, but they were later mowed due to excessive growth and the introduction of invasive weeds.

The East 10th Street exit was replaced with South Dakota's first single-point urban interchange in 1995, which required workers to direct traffic for confused motorists upon opening.

[45] A proposal from the state government to close access to 476th Avenue from the interchange in the 1990s was rejected following criticism from Minnehaha County and Sioux Falls officials.

It begins at the Highway 115 (SD 115) interchange along I-229 in the southern part of the city and follows Minnesota Avenue towards downtown Sioux Falls.

The Downtown Loop ends at a single-point urban interchange with I-229 in the eastern part of the city, while SD 42 continues east towards the Iowa state line.