Tantalus residents want to preserve the winding, historic roadway that straddles their mountain.

So in March, they secured a spot on the state Register of Historic Places for a seven-mile stretch of Tantalus and Round Top drives.

And now they are seeking its designation on the National Register.

The listings mean that any large-scale changes to the road must be put out for public comment and take into account its historical significance.

"The road is essentially as it was before World War II," said Barbara Shideler, a historical architect with Mason Architects in Honolulu.

Shideler helped research the history of the road for the registry application, and said its preservation is important to countless residents and visitors — not just those who live on Tantalus and drive it daily.

"It's a pretty remarkable resource in urban Honolulu," she said.

The beginnings of Tantalus and Round Top drives date to 1892. They were completed as gravel roads in 1917, and first paved in 1937.

The Tantalus-Round Top stretch is the first roadway on O'ahu to be placed on the state historic register. Kuhio Highway on Kaua'i and Hana Highway on Maui are on the state and national registers of historic places.

Pamela Burns, a Tantalus resident who started the push to preserve the upper portions of Tantalus and Round Top drives, said roads are an integral part of Hawai'i history — just as much as buildings.

"This and so many more roads deserve protection," she said. "In protecting our roads, we're preserving our island's historical character."

The preservation project has the support of several community groups, including the Tantalus Community Association and the Outdoor Circle.

With the roads on the state historic register, city officials will have to seek public comment and approval from the state Department of Land and Natural Resources before proceeding with any large improvements.

"We want to make sure there are certain characteristics of the road that don't change, that the footprint remains the same," Burns said.

The designation does not include the lower portion of Round Top Drive, and so will not affect an ongoing city-state project to rehabilitate the road. The lower portion of the road was damaged in mudslides last year.

Residents said they decided not to include the lower portion of the road in the preservation project because it has already been significantly changed over the years by several safety and repair projects.

Nationally, relatively few roads are recognized as landmarks.

According to Historic Roads, a national group dedicated to preserving old thoroughfares, there are 97 roads in the nation listed as historic.

Not all of those made it onto the National Register of Historic Places.

Some appear on the National Scenic Byway or All-American Road listings, administered by the Federal Highway Administration.

Reach Mary Vorsino at mvorsino@honoluluadvertiser.com.