New Hampshire Route 16

New Hampshire Route 16 (abbreviated NH 16) is a 149.75-mile (241.00 km) long north–south highway in the U.S. state of New Hampshire. Much of its length is close to the border with Maine. NH 16 is the main route from the Seacoast region north to the Lakes Region and the White Mountains. The section from Portsmouth to Milton is a controlled-access toll highway known as the Spaulding Turnpike. Between the Portsmouth Circle and Dover Point, US 4 is also routed along the Turnpike. The northern section of Route 16 is called the White Mountain Highway.

The southern terminus of Route 16 is at the Portsmouth Circle, intersecting with Interstate 95 and the US 1 Bypass. The northern terminus is at the Maine state line in Wentworth's Location, where it becomes Maine State Route 16.

There are three secondary state routes related to Route 16. Two loops from NH 16 are designated as New Hampshire Route 16A, and the northern NH 16A connects to both ends of the New Hampshire Route 16B loop.