Two of Duluth’s signature lighthouses have been added to the National Register of Historic Places, the latest landmarks to join city staples such as the Aerial Lift Bridge, Armory and Union Depot in earning the distinction.

The Duluth Harbor North Pier Light and the Duluth Entry South Breakwater Outer Light — beacons that illuminate either side of Duluth Harbor’s ship canal — were added to the registry in June.

The North Pier Light, built in 1910, can shine up to 16 miles and is still used for navigation. The black and white structure is 37 feet tall and accessible on foot via the ship canal’s north pier. Few changes were made to the lighthouse in the last century outside of routine maintenance, including repainting to limit corrosion.

“[North Pier Light] evokes feelings that recall the dedication to duty characteristic of lighthouse keepers throughout the course of United States history ... and serves as a lasting reminder of the importance of maritime commerce in Great Lakes history,” according to the U.S. Coast Guard application for the National Register listing.

“It embodies and exemplifies distinctive aspects of architectural design and engineering that were characteristic of early twentieth century lighthouses built on piers and breakwaters in the Great Lakes.”

South Breakwater Outer Light, the third lighthouse to stand at the end of the pier, can cast its green light up to 17 miles. The beacon, constructed in 1901, is connected to the red-roofed fog signal building.

“It is widely recognized as a prominent landmark in St. Louis County,” according to its application.

The lighthouses, which work together to mark a range for vessels entering the canal from Lake Superior, had their beams replaced with LED lights in 2014.

In 2000, Congress established a lighthouse preservation program that allowed federal agencies, local governments and nonprofits to obtain historic lighthouses at no cost if they agree to preserve the light’s historic features and make them accessible to the public.

A spot on the National Register allows the U.S. Coast Guard to donate or sell the structures, potentially transferring the high administrative costs of maintenance to another owner.