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Zoning Map Maintenance – Montgomery County Planning Department

The official Digital Zoning Map for the Maryland-Washington Regional District in Montgomery County, is adopted by the District Council under Division 59.2.2 of the zoning code. The Montgomery County digital maps are certified by the Planning Director. The certification is part of the digital zoning layer, which is permanently kept and maintained by the Planning Department.

Specifically, it is the ITI division who curates the ‘Zoning’ GIS layers and maintains the servers and websites used to disseminate this map. The official zoning map for Montgomery County is found at this address:

Zoning for some municipalities within the County are maintained independently and must be verified with them separately. These include: Rockville, Gaithersburg, Poolesville, Laytonsville, Barnesville, Brookeville and Washington Grove.


Zoning in GIS is comprised of a handful of individual layers. Zipfile snapshots of these layers are available for download in GIS format on our data downloads site.

Layer Definition
Euclidean Zoning blocks The main block boundaries identifying the base zone for parcels.
Overlay Zones Various overlay zones apply modifying factors to standards and uses normally found on the zoning blocks beneath them.
TDR Overlay A second overlay highlighting where additional density can be obtained through the TDR program.
Zoning history annotations Zoning case history and special exception notations
Parcel boundaries
Parcel Lot/Block annotations


Changes to the Zoning map

The zoning for a property can only be changed by a:

With the exception of Local Map amendments, these amendments are usually the result of a planning process with the planning board which is ultimately sent forward to the District Council for approval. Local map amendments are usually put forth by a private property owner to the District Council.

In either case, when a proposed change is adopted by the District Council, the ITI division incorporates the change. This means that the zoning GIS layers are changed. The zoning layers prior to the change are archived. Physical copies of the data and PDF map representations are mailed to Maryland SDAT, Montgomery County Department of Permitting Services, and the Montgomery County Office of Zoning and Administrative Hearings (OZAH). And most importantly, the official zoning map is updated with the change.

Many months can pass between zoning updates. Every time a zoning change is adopted, the zoning map also gets a countywide parcel boundary update. Occasionally when an important parcel correction or new development is made, a countywide parcel update will also be performed by ITI, even though no other zoning block change was adopted.

For more information about Montgomery County zoning please contact the ITI GIS Manager.