The primary purpose of the road is to bypass a densely built commercial strip on New Hampshire Route 9 (NH 9) in the eastern part of Concord.

The four-lane freeway actually begins a short distance west of I-93 at the north end of Concord's Main Street where US 202 turns east from US 3.

Further east is exit 3, I-393's last, to NH 106, which runs south past the commercial area around the Steeplegate Mall, and north to New Hampshire Motor Speedway and the Laconia region.

[3] A feasibility study conducted in the 1980s proposed a number of alignments that would have extended I-393 beyond its eastern terminus to a new interchange (exit 10) on the Spaulding Turnpike between Dover and Rochester.

After much work, it was deemed impossible and an upgrade of US 4, a road which closely follows the route of the first New Hampshire turnpike from the early 1800s, was studied and completed.