Ballston Row in Arlington. (Benjamin C. Tankersley for The Washington Post)

Emily Hamilton is a research fellow with the Mercatus Center at George Mason University in Arlington, where she focuses on urban economics and land-use policy.

In response to Amazon’s plan to place new “headquarters” in Northern Virginia and New York, Rep.-elect Alexandria Ocasio-Cortez (D-N.Y.) tweeted “displacement is not development.” Her sentiment reflects many Northern Virginians’ fears that new Amazon workers will contribute to rising rents, putting even more pressure on low-income residents. This fear has merit, but new jobs don’t have to mean displacement.

It comes down to a choice on the part of Arlington County policymakers: Revise local zoning rules to allow for new housing to accommodate new residents, or require a growing population to compete over a stagnant supply of housing.

To date, Arlington has been a nationwide leader on transit-oriented development and creating an inclusive suburb. But as the county continues to grow, it’s time to continue this tradition by creating opportunities for more people to live in all of Arlington’s neighborhoods.

In 1979, Arlington revised its General Land Use Plan ahead of Metro’s arrival. The plan permitted new high-rise buildings within one-quarter of a mile of each new Metro station and gave neighborhoods such as Ballston and Courthouse the character they have today. It allowed the county to grow while maintaining relatively affordable housing compared to other high-income, high-opportunity urban areas.

Arlington’s housing costs are less out of reach than housing in jurisdictions that have almost completely walled off development. The median Arlington rental is 26 percent of the county’s median income. Keeping rent below 30 percent of income is a generally accepted household budget guideline, so many county renters can afford their housing comfortably.

While this is little comfort to residents who earn below median income and struggle to afford housing, Arlington fares much better than other coastal suburban counties. In places such as Westchester County in New York or Palo Alto in the San Francisco Bay Area, even middle- and high-income households may struggle to find housing that their budgets can accommodate.

While Arlington stands out for its willingness to grow, its high-rise friendly areas are only a tiny proportion of the county’s land area. Only about one-quarter of Arlington housing units are single-family detached houses — and more than half of the population lives in multi-family buildings — but the majority of the county’s buildable land area is dedicated to single-family neighborhoods.

The county’s zoning reflects a compromise to make growth possible while preventing change in single-family residential neighborhoods. But how long can the status quo last?

Today, much of the land that was initially upzoned for Metro’s arrival has been developed. A few highly visible high-rises are under construction now. Once they’re completed, few sites will remain where new high-rise apartment and condo buildings will be feasible. And while zoning has blocked new housing supply in most of the county, it hasn’t prevented new construction that causes inconvenience to neighbors.

Particularly in North Arlington, many expensive, single-family homes are being replaced with new, even more expensive, single-family homes. Rezoning could allow for duplexes, fourplexes or townhouses — often termed “missing middle housing” — to replace single-family homes when owners want to sell. From the street, missing-middle housing can be indistinguishable from single-family homes, but it would allow many more people to take advantage of Arlington’s economic opportunities without displacing anyone.

County planners should also revisit accessory dwelling — or “granny flat” — regulations. Last year, reforms encouraged more homeowners to build self-sufficient accessory dwellings within their garages or basements. While a step forward, the rules still ban detached accessory dwellings in homeowners’ backyards, a minimally intrusive source of low-cost housing for single or retired residents and a rental opportunity that would allow homeowners to afford their mortgages more comfortably.

By allowing dense development near Metro stations, Arlington has prospered while avoiding the severity of the affordability crisis that’s plaguing other dynamic American regions. But following decades of growth, the county’s zoning code is now outdated. Amazon’s new office will account for just a portion of the job growth that the county will continue to experience.

Without new opportunities to increase our county’s housing supply, the displacement Ocasio-Cortez warns against is coming. But with modest changes in neighborhoods that have shunned new housing supply, the county could welcome many more residents without pushing out those who live here now.