Interstate 229 (South Dakota)

Interstate 229
I-229 highlighted in red and I-229 Downtown Loop in blue
Route information
Auxiliary route of I-29
Maintained by SDDOT
Length	10.84 mi[1] (17.45 km)
Existed	1958[2]–present
History	Completed in 1962
NHS	Entire route
Major junctions
South end	I-29 in Sioux Falls
Major intersections	SD 115 in Sioux Falls SD 42 in Sioux Falls
North end	I-90 / CR 125 near Sioux Falls
Location
Country	United States
State	South Dakota
Counties	Lincoln, Minnehaha
Highway system
Interstate Highway System Main Auxiliary Suffixed Business Future South Dakota State Trunk Highway System Interstate US State
← SD 224 → SD 230

Interstate 229 (I-229) is an auxiliary Interstate Highway located entirely within Sioux Falls, South Dakota, United States. It runs for approximately 11 miles (18 km) around the southern and eastern sides of the city, providing a bypass route and connecting I-29 and I-90. The freeway is generally four-to-six lanes wide and follows the Big Sioux River through parts of the city. I-229 also has a business route that provides access to downtown Sioux Falls from the freeway.

An eastern bypass of Sioux Falls was proposed in the 1940s by the city government and developed over the following decade by the state government. It was incorporated into plans for the Interstate Highway System, which was approved by the federal government in 1956, and assigned the designation of I-229 in 1958. Construction began that year and was completed in two sections: the southern half in 1961 and the northern half in 1962.

Since its completion, I-229 has had several interchanges added to serve new development in Sioux Falls. 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. Beyond the northern terminus at I-90, the freeway originally transitioned into a gravel road, which was paved in 2006.