227 Area Code – Rockville, Maryland: Location, Time Zone & History

Serving the western Maryland and Washington, D.C. suburbs, this numbering resource entered service on June 14, 2023 as a distributed overlay on the existing 301/240 area, a step regulators had approved as far back as January 2001 but only activated once a study projected that 301/240 central office codes would run out between April and June 2023. The lineage behind it stretches back further: 301 was one of the original 1947 area codes and once covered all of Maryland, before 410 split off in 1991 to serve Baltimore and the Eastern Shore, and 240 was layered on as an overlay in 1997, the state's first.

The region anchored by Rockville, with Frederick as its largest city, blends federal employment with a strong private-sector base. 227 reaches communities including Bethesda, Silver Spring, Hagerstown, and Waldorf, spanning dense inner suburbs close to the capital and smaller, more agricultural towns further out. That range shows up in daily life: commuters tied to federal agencies and contractors live alongside residents connected to the biotechnology firms clustered along the I-270 corridor and to the colleges and research institutions scattered through the area.

• Federal government and federal contracting
• Biotechnology and life sciences along the I-270 corridor
• Higher education and research
• Agriculture, tourism, and hospitality
• Logistics and manufacturing