By Neva Maxwell, Cook County Planning & Zoning Administrator - July 4, 2025

What if we could create more housing in Cook County—without sacrificing the woods, wetlands, and natural character that make this place so special?

On May 27, 2025, the Cook County Board of Commissioners unanimously approved a new zoning tool: the Residential Open Space Overlay (ROSO) District. This voluntary zoning option offers landowners a path to create additional housing in rural areas while preserving at least half of their land as undeveloped open space.

The key word here is “voluntary.” No one is zoning changes unless they choose to apply.

 What Is an Overlay District?

An overlay district works like a zoning add-on. It doesn’t replace the base zoning or change what’s currently allowed. Instead, it creates an optional path for development—available only if certain eligibility criteria are met and the landowner goes through a public review process.

In the case of ROSO, a landowner would need to apply for rezoning into the district. The process includes public hearings, notification to neighbors within a half mile, and specific location and design requirements. Because ROSO replaces the broader range of land uses in FAR-2 and FAR-3 zones with a narrower residential focus, it is considered more restrictive than the base zoning.

What Makes ROSO Different?

At the core of the ROSO District is a development pattern known as an open space subdivision (or conservation subdivision). This approach clusters homes on smaller lots and keeps at least 50% of the property in a natural, undeveloped state. In a place like Cook County—where ledge rock, wetlands, and forested terrain often make large-lot development difficult—this model supports smarter land use and can also reduce infrastructure costs through shared roads and utilities.

Under the ROSO District, eligible landowners may receive a residential lot density bonus—up to twice the number of parcels typically allowed under base zoning—in exchange for meeting open space requirements and accepting stricter land use limits.

For example: 

• A 20-acre parcel in FAR-3 (with a 5-acre minimum lot size) could allow up to 8 lots (instead of the standard 4 lots), with 10 acres preserved as open space.
• A 65-acre parcel in FAR-2 (10-acre minimum lot size) could support up to 13 lots (instead of the standard 6 lots), with 32.5 acres left undeveloped.

Balancing Ownership and Use 

Current zoning allows each parcel to include a home, a guest cabin, and a bunkhouse. ROSO subdivisions, however, allow only one dwelling per parcel and prohibit short-term rentals entirely. The intent is to support long-term housing for full-time residents—an approach that limits competition from the vacation rental market and aligns with the goal of community stability.

Where Does It Apply? 

Not every property is eligible. To be considered for ROSO, a parcel must:

• Be in the FAR-2 or FAR-3 zoning district;
• Be located within one-half mile of a state, county, or township road;
• Be at least 1,000 feet from the shoreline of a lake.

If a river or stream is present on the parcel, a 300-foot buffer must be included in the preserved open space. Applications must also show how the proposal protects key natural features and fits the surrounding landscape.

Why Now?

Cook County faces some unique challenges when it comes to land development. Only 9% of the county’s land is privately owned, and much of that is already developed or constrained by terrain. At the same time, demand for housing continues to grow—and the supply of buildable land remains limited and expensive.

In the Land Services Department, we hear regularly from people searching for a way to live here year-round—whether that’s first-time homebuyers, empty-nesters looking to downsize, or people relocating for work. Yet, in many cases, large-lot zoning and high development costs put ownership out of reach.

ROSO offers a practical, local solution. It is one more tool to:

• Make better use of challenging parcels with lots of wetlands;
• Encourage clustered development near existing roads;
• Reduce infrastructure and environmental impact;
• And promote long-term housing over short-term use.

Shaped by Community Input

The ROSO District wasn’t created in a vacuum. It evolved through conversations with many Cook County residents, local contractors, realtors, township boards, housing advocates, environmental groups, and landowners. Their input helped shape a district that is responsive to local needs while respecting the rural character of Cook County.

For Those Feeling Unsure

It’s understandable to feel cautious about changes to land use. New developments can raise concerns—about environmental impacts, traffic, aesthetics, or the long-term impact on a neighborhood. That’s why ROSO includes built-in safeguards: eligibility criteria, public hearings, conservation requirements, and enhanced developer agreements to clarify expectations and reduce risk.

A Tool That Reflects Cook County Values

Cook County’s Land Use Guide Plan begins with a statement that many of us connect with:
"We live in Cook County because this unique place and community is where we choose to thrive amid an unparalleled natural environment for which we are dedicated stewards."

ROSO honors that sentiment. It encourages thoughtful development in appropriate places, limits sprawl and offers more pathways for people to call Cook County home—without compromising the landscape we all value.

Want to Learn More?

• Review the final Ordinance language on the County Board’s May 27 Meeting. 
• Explore the interactive eligibility map.
• Submit a land use inquiry if you have a parcel you want to consider for ROSO.

Have questions? Contact the Land Services Department:
[email protected]

In Summary

ROSO won’t solve all of Cook County’s housing challenges—but it is a forward-looking, locally designed tool that can make a difference. If you are a landowner wondering whether this might apply to your property or just want to understand more about how this works, we invite you to reach out.

It is one more way we’re working to support our communities—while staying rooted in the landscapes that define Cook County.

County Connections is a column on timely topics and service information from your Cook County government. Cook County – Supporting Community.