US 1 Bypass heads northwest and has two at-grade intersections with Borthwick Avenue and Coakley Road/Cottage Street before it comes to a large rotary, the Portsmouth Traffic Circle, where it interchanges with I-95 and the southern end of the Spaulding Turnpike/New Hampshire Route 16 (NH 16) and the eastern terminus of US 4.

[3] Upon leaving the rotary, US 1 Bypass immediately interchanges with Woodbury Avenue, which provides access to downtown and directly serves the retail district of Newington.

The remaining stretch of highway ceases to be limited-access, with local businesses and parking lots straddling the roadway.

This ramp best serves SR 236 northbound, which connects to I-95, and US 1 southbound for drivers destined for southern Kittery, Badgers Island, or returning to Portsmouth.

[citation needed] The Maine–New Hampshire Interstate Bridge, carrying the bypass and railroads over the Piscataqua River, opened to traffic on November 8, 1940.