The area code 351 is located in Haverhill, Massachusetts.
Area code 351 serves Haverhill, Massachusetts, as part of an overlay with area code 978 in northeastern and north-central Massachusetts. Haverhill sits along the Merrimack River near the New Hampshire border, giving the code a strong cross-border and commuter connection. The 351/978 overlay means both area codes cover the same places, and local calls use 10-digit dialing. You’ll see 351 on new phone numbers assigned in the region, while many long-time lines still use 978.
Area code 351 covers Haverhill and several nearby cities known for industry, education, and historic mill districts. Major communities in the 351/978 region include:
Introduced in 2001, 351 helped expand number availability without changing existing 978 phone numbers. Haverhill is known for its shoe-making history and its riverside downtown, and the MBTA Haverhill Line links the city to Greater Boston. The overlay also reaches key attractions like Lowell National Historical Park, reflecting the area’s deep industrial roots. Businesses and residents across the region use both 351 and 978, so seeing either code on caller ID is normal.
Established: 2001 (Source: North American Numbering Plan Administrator, NANPA)
Key facts to know: 351 and 978 share the same geographic area, they operate on Eastern Time, and both landlines and mobile phones use the codes. The overlay helps keep local phone numbers available as the region grows. If you live, work, or study in Haverhill and surrounding communities, a 351 phone number is as local as 978 and connects you to the same services, schools, and landmarks across northeastern Massachusetts.