South Dakota Highways

Interstate 229 (I-229) in South Dakota runs just more than ten miles (16 km) mostly within the city limits of Sioux Falls, the largest city in the state. It runs from a trumpet interchange Interstate 29 in the southern extremities of Sioux Falls to Interstate 90 just north of Sioux Falls. In between, the interstate travels through parts of southern and eastern Sioux Falls.

Since its initial construction, I-229 had the distinction of being the only interstate in the country that transitioned directly from a four-lane concrete road to a two-lane gravel road. That ended in 2006 with the paving of 476th Avenue, the continuation of the highway beyond its northern terminus at the interchange with I-90.

I-229 begins at a trumpet interchange with I-29 just south of Globe University. I-229 travels to the northeast, passing north of the Avera Heart Hospital of South Dakota before going through several parks. A few miles to the northeast, just after the Cliff Avenue exit I-229 turns north and passes through metropolitan Sioux Falls. I-229 terminates at a partial cloverleaf interchange with I-90. Construction crews are currently improving this interchange, causing much congestion on the northern end of I-229 and on I-90 near the I-229 exit.

Legally, the route of I-229 is defined at South Dakota Codified Laws § 31-4-210.