301-XXX-XXX Phone Numbers

Area code 301, established in 1947 as part of the North American Numbering Plan (NANP), originally covered all of Maryland. But with population growth and increased demand for telephone services, area code 301 was split in 1991 to create area code 410 for the Eastern Shore and central Maryland. To meet the growing need for more phone numbers, area code 240 was introduced as an overlay to 301 in 1997. In 2012, another overlay, area code 227, was added.

Currently, area code 301 serves western, southern, and part of central Maryland. This includes Montgomery County, Prince George's County, Charles County, Frederick County, Washington County, Allegany County, Garrett County, and part of Howard County. Major cities and towns within this area code include Bethesda, Cumberland, Frederick, Gaithersburg, Hagerstown, Potomac, Rockville, and Silver Spring, spanning approximately 9,226 square miles.

Area code 301 includes several zip codes, each representing unique communities and neighborhoods. Notable zip codes include:

- Rockville: 20847 - 20853
- Gaithersburg: 20877 - 20885, 20898, 20899
- Frederick: 21701 - 21705, 21709
- Bethesda: 20810 - 20817, 20824, 20827, 20889, 20892, 20894
- Hagerstown: 21740 - 21749
- Silver Spring: 20901 - 20908, 20910, 20911, 20914, 20915

As of the 2020 U.S. Census, the estimated population of counties within the 301 area code is around 2.1 million. Rockville is among the most populous cities in this region, with approximately 69,000 residents. Gaithersburg follows closely with about 68,000 residents. Bethesda, a significant business hub, has around 64,000 people. Silver Spring, although its boundaries are undefined, is believed to house over 71,000 inhabitants.

The economy within area code 301 is diverse, with cities like Bethesda, Frederick, Gaithersburg, and Rockville thriving in sectors such as biotechnology, healthcare, and technology. Bethesda, located near Washington, D.C., attracts numerous government agencies, non-profit organizations, and multinational corporations.

In conclusion, area code 301 represents more than just a telephonic identifier—it is an integral part of Maryland's history, population, economy, and culture. As Maryland's first area code, it continues to play a crucial role in connecting individuals, households, and businesses within Maryland and beyond.