More than 80 years ago, a small group of Johns Hopkins researchers turned a former auto shop into a clandestine lab for weapons research. Today, the university’s Applied Physics Laboratory has about 9,000 employees. It’s the biggest private employer in Howard County and one of the top employers in the Baltimore metropolitan area.

Much of the work performed at the 461-acre property is classified, and the lab normally keeps a low profile. But over the past few weeks, it has caught the attention of pro-Palestine protesters, who set up an encampment at the Hopkins Homewood campus in Baltimore and said the university should sever its ties with the defense and weapons industries.

The Pentagon has awarded the Applied Physics Laboratory $12 billion over the past decade, making Hopkins the largest university recipient of Defense Department money.

The protesters reached an agreement with the university administration over the weekend and dismantled their encampment Sunday. But in a statement announcing the deal, the protester group Hopkins Justice Collective said the Applied Physics Laboratory “must remain a target of pressure in the pro-Palestine, anti-war, student movement.”

The lab traces its history to the attack on Pearl Harbor in December 1941, when Japanese planes launched an assault on a U.S. Navy base in Hawaii. That put pressure on the Navy to develop effective anti-aircraft missiles, according to archival reporting from The Baltimore Sun. At the time, missile fuses were triggered by timers or the impact with a plane. Hopkins convinced the government that its scientists could design a fuse that would allow missiles to blow up when they got near planes.

Hopkins soon set up a lab in an inconspicuous three-story building in Silver Spring built by a Chevrolet dealer. About 500 people came to work in Silver Spring, The Sun explained in a 1945 feature, but “not more than 60 knew the whole story.”

Eventually, about 1,000 people were working on “one of the best kept secrets of the war.” Dubbed the “VT fuze,” the device dramatically improved the effectiveness of anti-aircraft missiles.

The lab soon expanded to encompass an entire city block in Silver Spring, but it was clear that more space in a remote area was needed. The Sun reported in 1946 that experiments were starting to draw the ire of nearby residents, who accused researchers of creating “the loudest and shrillest noise that man has yet produced.”

Hopkins began acquiring land in southern Howard County, assembling about 290 acres near U.S. 29. The first facility opened there in 1954. The lab added new buildings every few years.

The research and development center made news for its defense contracting — as well as for inventions like “The Beast,” a 100-pound robot that looked like a forerunner to the Roomba. It skittered through the halls, occasionally startling scientists.

The lab also continued to pioneer missile technology for the Navy, famously developing the Tomahawk missile in the 1970s. A guided, long-range precision missile capable of delivering a nuclear warhead, the Tomahawk has been used in every major American-involved conflict since the Gulf War.

Access to the property is restricted, but a film crew stopped by in the 1990s, according to the history section of the lab’s website. An athletic apparel company filming a commercial with Cal Ripken needed a high-tech backdrop.

And last year, the Applied Physics Laboratory made international headlines when scientists slammed a spacecraft into a 525-foot-wide asteroid at 14,000 mph. That project showed it was possible to redirect asteroids and protect the earth from a catastrophic collision.

The lab now encompasses 20 “major” buildings on 461 acres of land in Howard County, according to its website. Unlike most privately owned land, it is exempt from property taxes.

The Sun reported in 1964 that Howard County tried to tax the property, claiming the facility was conducting research for profit. It assessed a 100-acre parcel at $6.1 million. But Hopkins successfully appealed the tax. The state attorney general advocated for the university, which argued that the lab was an educational facility. Today, that 100-acre parcel is assessed at $341 million, according to state records.

The lab’s revenue and employment have grown relatively quickly in recent years. A decade ago, it had about 5,000 employees and $1.2 billion in revenue. Today, the lab says it employs more than 8,800 people, and it had $2.3 billion of revenue in fiscal year 2023.

One out of every 25 jobs in Howard County is at the lab. It trails only the county’s public school system in overall employment.

The Applied Physics Laboratory has spent more than $2.5 million lobbying Congress over the past decade, according to federal records. About 70% of its revenue comes from the Defense Department. NASA is the second-biggest source.

The lab’s contract with the Navy, its largest defense agreement, ends in 2027, at which time the university and the Pentagon will have the option to extend the pact for another five years and $6.2 billion.