Where Things Stand on the Route 23 Corridor, Six Years After the Interchange Opened

Marengo has been building toward a single bet for more than a decade: that connecting the city to Interstate 90 and extending water and sewer service along the Route 23 corridor will attract the commercial development the city needs to grow its tax base. Six years after the interchange opened and with utility construction now underway, the corridor is still mostly farmland. But the infrastructure is arriving, and a new state grant this year signals that Springfield considers the investment worth continuing. ¹

The interchange itself opened in December 2019. It cost $33.4 million and gave McHenry County its first and only direct connection to I-90, filling a 17-mile gap between the nearest exits. It features Illinois's first roundabouts at an interstate ramp and handles roughly 4,800 vehicles per day. The Illinois Tollway's Move Illinois capital program covered most of the cost, with IDOT and Marengo splitting a local share. ²

But an interstate ramp surrounded by farm fields cannot attract development on its own. Without water and sewer service, the corridor is limited to uses that work with wells and septic systems. The city has been addressing that in three phases.

Phase 1 extends utilities near the Unilock facility south of the interchange. It is the furthest along, at a cost of $8.4 million, with completion expected by the end of this year. ³ Phase 2 continues from Unilock to Anthony Road for $3.75 million and is expected to start in 2026. Phase 3 reaches the interchange itself for an estimated $4.1 to $4.5 million. No start date is set for Phase 3.

City of Marengo, DCEO, McHenry County EDC

The funding behind this work is substantial, and almost all of it comes from outside the city. A $26.9 million DCEO grant from the Rebuild Illinois capital program is covering much of the utility construction. ¹ In 2025, the state awarded an additional $3 million Regional Site Readiness Grant, one of 24 statewide. ⁴ McHenry County approved a $750,000 loan from American Rescue Plan Act interest earnings in April 2025. And in 2024, the state legislature passed Senate Bill 951 authorizing Marengo to acquire the land needed for the extensions. ⁵

Why it matters: this is one of the largest state infrastructure investments in a McHenry County community. For a city whose entire General Fund budget is $6.49 million, the scale of outside funding is unusual and worth noting.

The corridor sits in a county enterprise zone, a state designation that offers tax incentives to new businesses. It is positioned midway between Rockford and O'Hare airports. The McHenry County Economic Development Corporation reports interest from solar panel and battery manufacturers. ⁴ But no major tenant has committed, and the development pattern faces a familiar sequencing problem: businesses want a workforce nearby before they build, while housing developers want businesses in place before they break ground.

Former Mayor John Koziol emphasized a "dig once" philosophy during his tenure: coordinate water, sewer, and road improvements so the corridor is not repeatedly torn up for separate projects, as reported by Shaw Local. ¹ That approach depends on timing. IDOT has programmed a $1.5 million overlay of Marengo Road from Airport Road to Route 23 in the 2026-2030 highway improvement plan. ⁶ Whether that aligns with the city's utility phasing will determine whether the corridor is built efficiently or piecemeal.

What comes next: Phase 1 completion later this year, followed by Phase 2 construction. The city will need to attract its first commercial tenants to the corridor to demonstrate the model works. Council discussions on development incentives and zoning for the interchange area are expected as the infrastructure nears completion.