What is now DE 30 south of Gravel Hill was built as a state highway in various stages during the 1920s and 1930s.

From this intersection, the route heads north on two-lane undivided Gravel Hill Road, passing to the east of Millsboro Pond.

The road runs through a mix of farmland and woodland with some homes, coming to a junction with Morris Mill Road/Mt.

Farther north, DE 30 has a junction with Springfield Road/Johnson Road before it reaches the community of Gravel Hill.

In Gravel Hill, the road crosses the Delmarva Central Railroad's Lewes Industrial Track line at-grade and comes to an intersection with US 9/DE 404.

turns north to form a concurrency with DE 30, with the road crossing an abandoned railroad grade just east of the terminus of the Delmarva Central Railroad's Milton Industrial Track line.

heads east along with that route and DE 30 continues north on Isaacs Road.

[3][4] The route heads away from Milton and crosses Sowbridge Branch as it passes to the east of Reynolds Pond.

At this point, the route gains a center left-turn lane and passes east of Bayhealth Hospital, Sussex Campus before it reaches an intersection with Wilkins Road, which provides access to and from the northbound lanes of DE 1 at an interchange.

[6][7] DE 30 has an annual average daily traffic count ranging from a high of 6,703 vehicles at the Fleatown Road intersection to a low of 3,455 vehicles at the Pettyjohn Road intersection.

In addition, the state highway was completed from Millsboro to north of Gravel Hill as an unpaved road, with a portion north of Gravel Hill becoming a paved county road.

[17] By 1994, DE 30 was extended west from Millsboro to Bi-State Boulevard between Laurel and Delmar.

The route continued west and crossed US 13 before becoming Dorothy Road and ending at Bi-State Boulevard.

[20] On February 29, 2016, construction began on a superstreet intersection at US 13; this project was completed on May 19 of that year.

[21] In 2021, the Delaware Department of Transportation (DelDOT) proposed eliminating the portion of DE 30 west of Millsboro.

was a 0.74 mi (1.19 km)[24] alternate route of DE 30 south of the city of Milford in the Cedar Creek area.