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area code

Biggest city:





Eastern (GMT -5)

Nearby area codes: 

Zip codes



Major Cities:

Baltimore, Germantown, Silver Spring, Gaithersburg, Rockville, Bethesda, Wheaton, Potomac, Olney, Takoma Park, Damascus, Colesville, Clarksburg, Glenmont, Poolesville, Ashton.


Average Income:





Unemployment Rate:

The 301 area code is a significant part of Maryland's telecommunications network, serving a large portion of the state. Historical Significance: The 301 area code is one of the original North American area codes established in 1947. Initially, it covered the entire state of Maryland, showcasing its importance in the early days of telephone communication in the region. Geographical Coverage: Over time, the coverage area of the 301 area code has been reduced due to the introduction of new area codes to accommodate growing telecommunication needs. After several splits, the most significant being in 1991 with the introduction of area code 410, the 301 area code now primarily covers the western and southern parts of Maryland, including parts of the Washington D.C. metropolitan area, such as Montgomery and Prince George's counties. Introduction of Overlay Area Code and Ten-Digit Dialing: Reflecting the continuous growth in telecommunication needs, the 301 area code received an overlay area code, 240, in 1997. This addition meant that ten-digit dialing (area code + phone number) became mandatory in the region, marking a significant shift from the traditional seven-digit dialing and heralding a new era in the area's telecommunication infrastructure. These facts collectively provide a snapshot of the 301 area code's evolution from serving the entire state of Maryland to its current role covering specific regions, adapting to the growing and changing demands of telecommunication in the state.
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