Saugatuck’s iconic Mount Baldhead Radar Annex listed in the National Register of Historic Places

The iconic radar ball high atop Saugatuck’s Mount Baldhead has long been a well-known community landmark. Now it is also listed in the National Register of Historic Places.

The Michigan Economic Development Corp. announced the Saugatuck Gap Filler Annex’s new status this month. The decommissioned radar station was a part of a network installed to protect the country against Cold War attacks from the Soviet Union.

The Saugatuck City Council established the Mt. Baldhead Radar Station Workgroup in 2021 to protect, preserve, and promote the radar station. The group was instrumental in stabilizing the equipment building and securing the site, preparing it for future preservation efforts.

The efforts created community interest, says Saugatuck City Council Member Russ Gardner.

“It stands as a historical gem and the crown jewel of the city’s Mt. Baldhead Park,” Gardner says. “Without the support of the city and a multitude of volunteers, who collaborated to get this project underway, the National Register project would not have happened.”

Mt. Baldhead in Saugatuck is a favorite climbing spot of tourists. The radar station at the dune's peak is now on the National Registry of Historic Places.
Ametur Cold War historian Chuck Gustafson led research efforts to nominate the Saugatuck Gap Filler Radar to the National Register of Historic Places.

“I have had a fascination with early electron tube, computer, and radar technology for as long as I can remember. The combination of those in the Saugatuck gap filler radar is irresistible,” Gustafson said. “The equipment in the radar annex is a rare snapshot of that brief period where emerging digital electronics had not quite left vacuum tube electronics behind. This is the only piece of the Cold War era Semi-Automatic Ground Environment (SAGE) air defense system in public hands that remains in place nearly as it was while serving in the Cold War. To participate in nominating the Saugatuck radar to the National Register was the opportunity of a lifetime.”

The National Register of Historic Places is the federal government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation for their historic significance. It is administered in Michigan by the State Historic Preservation Office.

More than 96,000 properties across the country, including nearly 2,000 in Michigan, have been listed in the National Register since the program began in the 1960s. The National Register is a program of the National Park Service and is administered by individual states.

To be considered for listing in the National Register, a property must generally be at least 50 years old and must have historical significance.

“A key aspect of the National Register program is to document and honor places that are associated with events that have made a significant contribution to the broad patterns of our history,” says Michigan’s Deputy State Historic Preservation Officer Martha MacFarlane-Faes. “The Saugatuck Radar and the groundbreaking technology it once employed was an important piece of our national defense infrastructure during the height of the Cold War.”

The 230-foot Mount Baldhead sand dune sits between downtown Saugatuck and Lake Michigan. Tourists daily climb the dune’s 304 stairs for the view at the top. The Saugatuck Gap Filler at the dune’s peak was constructed in 1957 to address the threat of an air attack of Soviet planes flying from the north over the North Pole in the 1950s and 1960s, during the period known as the Cold War and can be seen from miles around.

After World War II ended in 1945, the wartime allies United States and the Soviet Union quickly became adversaries in a quest for industrial, technological, and military superiority. Advancements in weapons, missiles, and space technology came rapidly amid fear of an enemy attack. Throughout the Cold War, the world was immersed in an unrelenting sense of impending nuclear doom as both countries engaged each other through proxy wars and traded military and political feints. In the United States, air raid siren tests, duck-and-cover drills, and “we interrupt this program” announcements punctuated the endless waiting-in-dread anticipation of the rumble of Soviet nuclear bombers approaching over the northern horizon or the silent fall of a nuclear missile.

In North America, the potential for an air attack of Soviet planes was seen as a credible and constant threat. An immense continent-wide network of automated and manned radar installations that sought to identify, track, and respond to airborne attackers was quickly being built. This system was controlled by the most capable real-time digital computers of its era and led the cutting edge of digital processing, networking, and communications.

But there was a weakness in the radar armor. High-power radar installations could “see” far into the skies, but could not identify potential aircraft flying at low altitude or near hilly terrain. These gaps in the system could present an opportunity for literal “under the radar” attacks. Special “Gap Filler” radars were needed to scan the horizon in these specific areas.

The Saugatuck Gap Filler became operational in 1958 with a specific mission to search the skies over Lake Michigan where enemy planes might target Chicago or the steel mills of Indiana. The radar antenna atop the dune spun relentlessly, feeding data into vacuum tube storage equipment being transmitted continuously via telephone lines to the Custer Air Force Station near Battle Creek.

Dozens of Gap Filler radars were built across the country to scan for attack and used the first modem ever used in a practical application.

When the Saugatuck radar station was upgraded with higher-power radar equipment in 1963,  the radar antenna atop the tower was enclosed in the white globe-shaped “radome” made of fiberglass, which is a beloved Saugatuck icon today.

The gap filler was in use for only a short time. By the late 1960s, the threat of aircraft attack was quickly being overshadowed by the threat of intercontinental ballistic missiles, which fly too high and too fast for gap filler radars to recognize.

By the end of the decade, the city of Saugatuck bought the unused site. While other such radar stations were torn down across the country, the remains of the Saugatuck Gap Filler have sat silent.

Of 131 Gap Fillers known to have been built, Saugatuck’s is believed to be one of just a small handful, and the most technologically complete, which remains.

“The white radar ball is one of the most visible landmarks in Saugatuck and nearby Douglas, but the real significance is the technology which was used inside the ball and in the diminutive bunker building below,” said Michigan SHPO Project Coordinator and lead nomination reviewer Nathan Nietering. “The radar installation at Saugatuck played a very real role in protecting our nation, even though the feared Soviet air attack never came to be. The Cold War sped up the development of groundbreaking technology such as real-time computing, interactive graphics, modems, and wide area networking, and the Saugatuck Gap Filler still embodies this incredible period of history.”