Howard County, Maryland

Howard County, population 325,690 (2019), is located 20 miles southwest of Baltimore and 30 miles north of Washington, DC. The County has a Density Exchange Option aimed at preserving farmland.

Howard County uses TDR to preserve farmland.


As of 2021, the Density Exchange Option (DEO), Section 106 of the Zoning Code, allows sending sites to be approved on parcels within the DEO Overlay District zoned Rural Conservation (RC) that are capable of accepting a conservation easement of at least 20 acres in size. One development right is created per three acres preserved. Although a parcel zoned RC can be either a sending or receiving parcel, a single property cannot be both a sending and receiving site.

Receiving sites are also within the DEO Overlay and zoned either RC or Rural Residential (RR). However, receiving sites zoned RC must be less than 50 acres in size and be adjacent to properties no greater than 10 acres in size on 60 percent of their perimeter. 

In a variation known as Cluster Exchange Option (CEO) one development right can be created per 4.25 acres preserved and receiving sites must be within the DEO Overlay and zoned RC.

On both the DEO and CEO receiving sites, baseline density is one dwelling per 4.25 acres. Each development right allows one bonus unit on a receiving site up to a maximum density of one unit per two acres. Additional rules apply for certain minor subdivisions.  

Receiving sites must be designed to cluster development in ways that maximize preserved farmland, minimize conflicts with farming operations, and protect rural and scenic quality, especially as seen from public roads.  Receiving site developers can use TDRs by right, a feature found in many successful TDR programs because it relieves developers of the uncertainty, cost, and delay often associated with discretionary processes. As of 2016, the Howard County program had protected 4,980 acres (Maryland 2016).


Maryland. 2016. Transfer of Development Rights Committee Report. Maryland Department of Planning. Accessed 1-29-21 at TDR-committee-report-2016.pdf (