Is Illinois a home-rule or Dillon's Rule state?

Illinois is mixed. Under Article VII of the 1970 Constitution, municipalities over 25,000 population (plus any smaller municipality that votes to opt in) are automatically home-rule and can exceed the state's express zoning grants; all other municipalities and counties operate under Dillon's Rule via the Illinois Municipal Code (65 ILCS 5/11-13-1) or the Counties Code (55 ILCS 5/5-12001).

How do I look up zoning for a parcel in Chicago or Cook County?

RealDevelop covers all 1,396 tracked Illinois jurisdictions and provides parcel-level zoning lookup across the full 2.62-million-parcel Chicago metro dataset spanning Cook, DuPage, Kane, Lake, McHenry, and Will counties; outside that footprint, zoning maps are published individually by each municipality or county.

Can I build an ADU in Chicago?

Only within the designated pilot areas. Chicago's 2021 ADU ordinance permits coach houses and basement units by right in five pilot areas spanning the North, Northwest, West, South, and Southeast sides; outside those areas, an ADU generally requires a zoning variance or special approval.

What is Chicago's Connected Communities Ordinance and does it affect my project?

Passed in July 2022, it is Chicago's transit-oriented development framework: it doubled the radius around rail stations (and added eligible bus corridors) where projects qualify for reduced parking minimums and density bonuses in exchange for affordability commitments.

Illinois · state zoning reference · Live at parcel level

Illinois zoning: how it works and what you can build

RealDevelop's home turf: Illinois splits zoning power between home-rule municipalities (Chicago and Cook County chief among them) and hundreds of independent, non-home-rule suburbs, producing one of the most fragmented zoning landscapes in the Midwest — RealDevelop already tracks all 1,396 Illinois jurisdictions.

How zoning works in Illinois

Illinois is a mixed home-rule state under the 1970 Constitution: municipalities over 25,000 population (plus any smaller municipality that votes to opt in) are automatically home-rule, giving them zoning and land-use powers beyond what state statute expressly grants; all other municipalities and non-home-rule counties operate strictly within their statutory authority. Chicago and Cook County are both home-rule, which is why the city has been able to layer TOD overlay districts, inclusionary requirements, and density bonuses on top of its base zoning ordinance without waiting on state enabling legislation.

Municipal zoning power comes from the Illinois Municipal Code (65 ILCS 5/11-13-1 et seq., Division 13), which authorizes municipalities to divide their territory into districts and regulate use, bulk, and density. County zoning power over unincorporated land comes from the Counties Code (55 ILCS 5/5-12001 et seq.); within any municipality's corporate limits, municipal zoning always supersedes county zoning.

RealDevelop covers Illinois more deeply than any other state: 2.62 million parcels are live across the six Chicago-metro counties (Cook, DuPage, Kane, Lake, McHenry, and Will), spanning 255 jurisdictions with full zoning maps, and all 1,396 Illinois jurisdictions statewide are tracked. The platform's Chicago TOD engine specifically models the city's 2022 Connected Communities Ordinance density and parking bonuses.

Chicago's Connected Communities Ordinance (passed July 2022) is the state's most consequential recent zoning reform: it doubled the radius around rail stations eligible for reduced parking minimums and density bonuses and added eligible bus corridors, in exchange for affordability commitments. It built on a narrower 2021 ADU pilot program that permits coach houses and basement units by right in five designated areas of the city.

Who holds the zoning power

Land-use authority in Illinois is delegated by statute, not assumed — these are the acts a zoning ordinance in Illinois has to trace back to.

Illinois Municipal Code (Zoning) 65 ILCS 5/11-13-1 et seq.: Enables municipalities to adopt zoning ordinances dividing territory into use, bulk, and density districts
Illinois Counties Code (Zoning) 55 ILCS 5/5-12001 et seq.: Enables non-home-rule counties to zone unincorporated territory outside municipal limits
Home Rule Illinois Constitution, Article VII: Grants municipalities over 25,000 population (and any county with an elected chief executive, i.e. Cook County) home-rule powers exceeding express statutory grants, including expanded zoning authority

Major cities and their codes

The enabling act sets the ceiling; the municipal code is what a project is actually reviewed against. The 8 largest Illinois jurisdictions and the codes they administer:

Illinois — municipal zoning codes
City	Zoning code
Chicago	Chicago Zoning Ordinance (Municipal Code of Chicago, Title 17) Home-rule city; Connected Communities TOD bonuses and an ADU pilot program covering five areas of the city
Aurora	Aurora Zoning Ordinance Illinois's second-largest city, spanning Kane, DuPage, Will, and Kendall counties
Naperville	Naperville Zoning Ordinance High-value DuPage/Will suburb with strict design review standards
Joliet	Joliet Zoning Ordinance Will County industrial and logistics corridor growth
Elgin	Elgin Zoning Ordinance Kane/Cook border city with TOD potential around its Metra line
Rockford	Rockford Zoning Ordinance Northern Illinois's largest city outside the Chicago metro core
Peoria	Peoria Zoning Ordinance Central Illinois river city with an active downtown redevelopment push
Springfield	Springfield Zoning Ordinance State capital, central Illinois

Recent reforms

State-level changes override or preempt what a local ordinance says — these are the Illinois reforms that move the numbers on a real site.

2022 Connected Communities Ordinance Chicago's transit-oriented development overhaul: expanded TOD-eligible radius and bus corridors, reduced parking minimums, added affordability requirements for density bonuses
2021 ADU Pilot Program Chicago's original ordinance permitting coach houses and basement units in five pilot areas across the North, Northwest, West, South, and Southeast sides

Parcel & GIS data

RealDevelop ingests parcel and zoning data for all 1,396 tracked Illinois jurisdictions, with full parcel-level GIS coverage (2.62 million parcels, 20 metro zoning maps) live across the six Chicago-metro counties; Illinois has no unified statewide parcel portal, so coverage outside the metro core is sourced county by county.

Zoning by city

The statute sets who may zone; the city's own code sets what you can build. One guide per Illinois city below, explaining the district codes that appear on its zoning map — 106 district codes across Illinois so far.

Illinois zoning — common questions

Is Illinois a home-rule or Dillon's Rule state?: Illinois is mixed. Under Article VII of the 1970 Constitution, municipalities over 25,000 population (plus any smaller municipality that votes to opt in) are automatically home-rule and can exceed the state's express zoning grants; all other municipalities and counties operate under Dillon's Rule via the Illinois Municipal Code (65 ILCS 5/11-13-1) or the Counties Code (55 ILCS 5/5-12001).
How do I look up zoning for a parcel in Chicago or Cook County?: RealDevelop covers all 1,396 tracked Illinois jurisdictions and provides parcel-level zoning lookup across the full 2.62-million-parcel Chicago metro dataset spanning Cook, DuPage, Kane, Lake, McHenry, and Will counties; outside that footprint, zoning maps are published individually by each municipality or county.
Can I build an ADU in Chicago?: Only within the designated pilot areas. Chicago's 2021 ADU ordinance permits coach houses and basement units by right in five pilot areas spanning the North, Northwest, West, South, and Southeast sides; outside those areas, an ADU generally requires a zoning variance or special approval.
What is Chicago's Connected Communities Ordinance and does it affect my project?: Passed in July 2022, it is Chicago's transit-oriented development framework: it doubled the radius around rail stations (and added eligible bus corridors) where projects qualify for reduced parking minimums and density bonuses in exchange for affordability commitments.

Live at parcel level

Illinois is live — run a real parcel.

Illinois is the state where the reference above stops being a reference. Parcel-level feasibility runs across the Chicago metro: 2.62M parcels ingested across 255 jurisdictions in all 6 metro counties, with all 1,396 Illinois jurisdictions tracked for coverage. Type an address or a 14-digit PIN and you get the parcel's zoning district, lot dimensions, transit status, buildable envelope and a generated massing scheme — every figure carrying its § citation.

The Chicago zoning reference — all 53 districts (RS, RT, RM, B, C, D, M) with FAR, height, lot area per unit, setbacks and parking, each figure cited to Title 17 of the Municipal Code.
Connected Communities / TOD — the transit ordinance that cuts parking minimums and adds FAR, height and density on qualifying lots.

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Illinois zoning summaries on this page are provided for information, not legal advice. Confirm every project against the current adopted code for the jurisdiction and the statute as amended.