The idea of a zoning code was first introduced in early 1900s and dramatically changed the way land ownership was viewed in the US. In a 1926 landmark case Euclid v. Ambler the Supreme Court ruled in favor of the Village of Euclid, Ohio and upheld its zoning ordinance that prevented Ambler Realty from developing 68 acres into an industrial park.

Early zoning codes focused on separating residential areas for industrial nuisances and regulating height and intensity of land use (i.e. Washington, DC 1899). However, in many cases they became tools for racial segregation. Baltimore passed the first racially based zoning ordinance in 1910 and this practice quickly spread, mainly in the Southern US cities. In 1917, US Supreme Court declared Louisville, Kentucky’s racial zoning ordinance unconstitutional on the basis of violation of the Fourteenth Amendment. But the practice of segregation disguised in zoning laws persisted while cities hired sophisticated planners to draft ordinances that would be defensible in courts.

Denver’s first zoning code dates to 1925 when, under Mayor Stapleton, the city was divided into residential, commercial, and industrial areas. The ordinance was to promote the “health, safety, morals, or general welfare.” The predominantly white areas of town were zoned single family while areas occupied by minorities were more likely to be zoned for multifamily housing. The political influence of the Ku Klux Klan prevented minorities from geographic migration.

The 1955 Denver zoning code further exacerbated the city’s existing racial and social divisions. Residential zoning was divided into four categories from the most restrictive R-0 that prohibited renting out any parts of the property, R-1 (single family), R-2 that allowed duplexes and townhomes, and R-3 and R-4 that allowed multifamily housing. The code also defined “family” as a group of people related by “blood, marriage, and adoption” and defined R-0 zoning as areas where “children and their parents would thrive” excluding non-traditional households.

In 2010, Denver adopted a “form-based” code that promised to focus on building forms rather than segregation of uses. However SU (Single Unit) and TU (Two Units) designations are still present in the mapping and descriptions of the building forms. Moreover vast areas that were zoned R-2 under the previous code were downzoned to SU.

This brings us to the current day and the vision of “complete neighborhoods” outlined in the new Blueprint Denver plan. Complete neighborhoods are defined as accessible to all regardless of age, ability, or income, and providing housing options for all people. Our land use regulations no longer exclude minorities and we strive for inclusivity. However, Denver’s established neighborhoods lack diversity of housing inventory, particularly affordable rentals. Moreover, they are expected to absorb 10% of Denver’s anticipated growth of 200,000 new residents.

Examples of how small multi-family dwellings can integrate with single-family dwellings to create complete neighborhoods while maintaining the neighborhood’s built character.
Diagram of how small multifamily homes can be compatible with single-family housing. Source: Gosia Kung

As Denver moves to adopt and implement the new Blueprint Denver plan, we can use the zoning code to achieve the vision of complete and diverse neighborhoods. We should consider relaxing the zoning code to allow low-to-mid density building forms and ADUs (Accessory Dwelling Units) in all residential neighborhoods, particularly in areas within walking distance (half-mile) of transit corridors. By allowing up to four units in already existing building forms (Urban and Suburban House) and expanding the vocabulary of available forms, we can create neighborhoods that are both respectful of historic character and affordable and accessible to all residents.

The Racial Origins of Zoning in American Cities by Christopher Silver
R-0: Race, Sexuality and Single Family Zoning in Denver’s Park Hill and Capitol Hill Neighborhoods, 1956-1989 by B. Erin Cole