ISG Strengthens West River Presence with ARC International in Rapid City

Rapid City, South Dakota, April 3, 2026 – ISG, a full-service architecture and engineering firm, has acquired ARC International, a Rapid City architecture firm. Known for place-sensitive design, ARC International delivers solutions that do more with less and feel native to their surroundings. With 27 years serving Rapid City, the team deepens ISG’s commitment to local clients and represents a strategic investment in growing ISG’s architecture team, enhancing the firm’s ability to serve communities across South Dakota.

ARC International’s portfolio includes the Black Hills Energy Horizon Point Headquarters in Rapid City, numerous projects at Ellsworth Air Force Base (EAFB) in support of EAFBs mission with the B-21, ongoing work with schools in our communities, and the design and expansion of many businesses and organizations across the Black Hills and West River, South Dakota. The creative team will continue serving clients throughout South Dakota and the six surrounding states with the same people they know and trust, now supported by ISG’s in-house architecture, engineering, environmental, and planning resources.

“I am proud to see the firm I started in 1999 step into its next chapter,” said Donovan Broberg, founder of ARC International. “With ISG, we strengthen our ability to deliver thoughtful, creative solutions for our clients while continuing our long-standing commitment to our Black Hills Region, helping clients navigate complex projects with clear, purposeful design.”

By uniting two firms that share a commitment to exceptional service, ISG advances its mission to make a difference. The firm has been involved in projects statewide, including economic development infrastructure planning for the South Dakota Governor’s Office of Economic Development. This initiative focused on identifying statewide opportunities to advance infrastructure and spur economic growth, as well as supporting planning for 16 communities with under 5,000 residents. With the ARC International acquisition, ISG establishes a permanent presence in Rapid City, joining offices in Dakota Dunes, Sioux Falls, and Pierre, and enhancing its ability to support communities across western South Dakota.

“Adding ARC International strengthens how we serve South Dakota,” shared ISG CEO Lynn Bruns, PE. “This addition expands our capacity to deliver the responsiveness and quality our clients expect across South Dakota.”

Establishing a presence in Rapid City also creates new opportunities for collaboration with South Dakota Mines. With an office closer to campus, ISG looks forward to working alongside faculty and students, recruiting interns and graduates, and supporting the region’s workforce pipeline.

As a 100% employee-owned firm, ISG’s investment is centered on long-term community involvement. In Rapid City, employee owners will remain actively engaged through local organizations, community initiatives, the ISG Impact Fund and Impact Day, which includes eight paid volunteer hours each year.

This acquisition brings a trusted Rapid City team together with ISG’s statewide partners and clients. The combined team will continue serving Rapid City and the region with a stronger local presence and expanded in‑house capabilities.