Imagine if a city or county adopted a future land use plan with three residential categories:

Households earning more than $200,000.

Households earning $100,000 to $200,000.

Households earning less than $100,000.

Americans would immediately recognize the problem. No modern municipality would openly create a map dividing residential opportunity according to income.

But change the terminology.

Large-lot detached housing here. Medium-density housing there. Townhomes around this node. Apartments along that corridor. Duplexes and fourplexes prohibited throughout most of what remains.

Suddenly, it looks like conventional land-use planning.

The map never mentions income. It doesn’t have to.

We don’t have to zone people by income when we zone the housing products their incomes allow them to purchase.

Forsyth County, Georgia, provides an interesting example of how these decisions are made.

The county’s comprehensive planning process uses character areas and development nodes to help determine where different types and intensities of residential development are considered appropriate. During Forsyth County’s 2022 comprehensive-plan process, officials considered where MRD—Medium Residential Density—should be appropriate.

Meeting records show MRD opportunities being removed from a number of character areas and nodes, including Haw Creek, Lanier, Vickery Creek, the Highway 20 Community Node, the Highway 20 Neighborhood Node, Chestatee/Jot Em Down and Etowah.

During those discussions, one participant warned that “not having a compact residential opportunity in the nodal areas is getting away from the intent behind the creation of the nodes.”

That discussion illustrates something important about housing affordability.

Residential opportunity doesn’t simply emerge from the market. Before the developer buys the property, before the builder selects a house plan and long before a family walks into a sales center, government has helped determine where different residential densities will be considered appropriate.

And at a time when housing affordability has become a serious problem, Forsyth County’s planning process appears to have removed opportunities for medium-density housing from several areas where it had previously been contemplated.

Why does that matter?

Consider two pieces of residential property.

Both have sewer and water. Both have adequate roads. Both can satisfy legitimate environmental, engineering, fire, stormwater and infrastructure requirements.

But the government’s future land use plan makes two homes per acre appropriate on one property and six homes per acre appropriate on the other.

The physical capacity of the land didn’t necessarily change.

The policy did.

Now put numbers to it.

If an acre of residential land costs $300,000, developing two homes per acre begins with $150,000 of raw land allocated to each home. Developing six homes per acre begins with $50,000.

That is a $100,000 difference per home before a foundation is poured, a wall is framed or a roof is installed.

Density isn’t simply a planning term.

Density affects price. And price determines who can afford to live there.

I am not suggesting that Forsyth County commissioners or planners intended to segregate residents according to income. I don’t believe they did, and that isn’t the point.

The more important question is whether our planning system can produce economic separation without anyone intending to create it.

Government determines where different housing types and densities are appropriate. The landowner reacts to those boundaries. The developer reacts. The builder reacts. Eventually, the homebuyer encounters the result as a selection of houses at particular prices in particular locations.

By the time that family walks into a sales center, the government decision that helped determine what could be built there may have been made years earlier.

We call it land-use planning.

The family experiences it as what they can—or cannot—afford.

This is where I believe we need to reconsider the basic premise behind the way American communities plan residential land.

Why should a future land use plan determine the income level necessary to live in different residential areas when infrastructure and legitimate health and safety requirements could determine what the land can support?

If a piece of property can safely support residential development, perhaps our future land use maps should say something much simpler:

Residential.

Then let infrastructure determine what the land can support and allow the market to determine what people need.

One builder might build a traditional detached home on a wider lot. Another might build a 1,200-square-foot detached home on a narrow lot. Another might build a duplex. Somewhere else, townhomes or a small apartment building might make sense.

Those housing types do not have to be isolated from one another.

More importantly, the people who can afford those different housing types do not have to be isolated from one another.

Teachers could live near executives. Firefighters could live near doctors. Police officers could live near attorneys. Young couples buying their first home could live in the same neighborhood as families buying their third.

That isn’t radical planning.

For much of American history, we simply called it a neighborhood.

The housing affordability debate usually begins too late. We talk about mortgage rates, down-payment assistance, tax credits, subsidies and government housing programs after the price of the home has already been established.

But the cost of housing begins much earlier.

It begins when government determines how much land must accompany each house. It begins when government determines which housing products may be built. And it begins when a line on a planning map determines that one part of a community may accommodate more homes while another may not.

We would never knowingly draw a map saying families earning less than $100,000 may live here, while families earning more than $200,000 may live over there.

Perhaps we should ask whether we have created a more sophisticated way of accomplishing much the same result.

We don’t zone income. We zone the things income buys.

And if America is serious about housing affordability, that is a conversation worth having.

Jay Knight is a Georgia residential developer and the author of Zoned Out: How Cities and Counties Make Homes Unaffordable. He has worked in residential construction, real estate and land development since 1978.