Interstate 29 20th Street South Interchange

Drone photo looking northwest.

This new interchange will provide another connection between the residential areas on the west side of I-29 and the large employment centers on the east side of I-29. It will also provide I-29 access for the rapidly developing south side of Brookings.

November 9, 2022

Construction Updates

  • The 22nd Avenue/20th Street intersection is now open to traffic. Adjustments to the signals have been made to account for current traffic movements.
  • I-29 traffic is now using a single lane of the both the east and west sides of I-29. All lanes of I-29 will be open to traffic soon.
  • The contractor has been spreading gravel on 20th Street and the ramps.
  • Journey Construction has finished their work on the new bridge.
  • Along I-29:
    • Cable guardrail is being installed.
    • Asphalt shoulder work is being completed.

View a map of the project area.

Project Timeline

Project timeline

Frequently Asked Questions

All work is to be completed by July 14, 2023.

The winning (low) construction bid was $15,305,307.53 submitted by local contractor Bowes Construction, Inc. The engineer's estimate for construction was $15,848,975.85. Four contractors submitted bids for the November 17, 2021 bid letting.

In November 2019, the project received a grant from the US Department of Transportation for 80% of the overall project cost (including engineering, right-of-way acquisition, permitting and construction). The remaining 20% of the project cost is paid by the City of Brookings, Brookings County, and private donors.

For many years, the City of Brookings has recognized the need for another east-west crossing of I-29 to connect the residential areas on the west side of I-29 to the large employment centers on the east side of I-29.

The new I-29/20th Street South interchange provides that connection and also provides convenient I-29 access to the rapidly developing south side of Brookings.

An Environmental Assessment was prepared, released to the public, and approved by the Federal Highway Administration. Other approvals and/or permits were secured from US Army Corps of Engineers, US Fish and Wildlife Service, SD State Historic Preservation Office, SD Department of Game, Fish and Parks, Federal Emergency Management Agency, City of Brookings and Brookings County Floodplain Administrators, City of Brookings Parks, Recreation, and Forestry Department. Seven area Native American tribes were also given an opportunity to comment on the project.

Impacts to adjacent properties were the main environmental factors that led to the selection of the final option now under construction. Minimization of impacts to Edgebrook Golf Course was of special concern because purchase of the golf course property and construction of the golf course utilized federal funding. See the Environmental Assessment Presentation for a summary of the considerations.

COVID-19 limited the opportunity for Public Meetings. Project information was provided to the public via informational releases on the project website on April 20 and October 19, 2020. Notice of the website releases was done via postcards, newspaper notices, and City of Brookings and SDDOT press releases. Comments from the public were submitted to the website and responses were posted on the website.

During construction, see the contacts at the bottom of this site.


The City of Brookings has been considering a new I-29 interchange at 20th Street for nearly 20 years. Award of a US Department of Transportation grant for the project in November 2019 initiated the "official" environmental and traffic study and engineering design phase of the project. See below for a few key documents pertaining to the evaluation, design, and environmental approval of the project.

Project Partners