The year 2016 saw a lot of talk about the state of American manufacturing—about jobs making stuff for great American brands. And while most of the discussion centered on products like General Electric lightbulbs and Carrier air conditioners, it’s worth pointing out one brand that’s received very little press—even though all of its manufacturing takes place in the U.S. (in Colonial Heights, Va.); even though untold numbers of the 500 million products it turns out yearly are used every day of the week.

Well, maybe more like every night of the week. The product? Trojan condoms.

Condoms are big business in the land of the free. According to Zion Research, Americans are forecast to spend nearly $1.6 billion on them by 2020. And the vast majority of the market share—over 72 percent by one estimate—belongs to Trojan.

Trojan, the brand started by the Youngs Rubber Company, turned 100 years old in 2016. That makes the year’s end a good time to look back at the brand that not only dominates its segment, but—forgive us—turned America on to condoms in the first place. (Check out the complete photo gallery below.) Much like Kleenex and ChapStick, Trojans have become synonymous with their category. And, as corporate hastens to point out, since introducing its signature product in 1916, Trojan has been “America’s No. 1 condom brand.”

But getting there hasn’t been simple. These days, nobody flinches at the kind of straightforward advertising Trojan did this past summer—those humorous spots starring Lil Dicky, or the Snapchat ad showing two spring-breaking millennials getting their “party on.” Marketing like 2010’s “Live Large” contest, which crowdsourced songs with lyrics about Magnum extra-large condoms, has reportedly made Trojan the top-dog brand among African American men.

But for the first five decades of the company’s existence, there was no consumer marketing to speak of. Before the sexual revolution loosened things up in the early 1970s, if a fella wanted to buy condoms, his sole option was to ask the local druggist for them—and they were all behind the counter.

And according to the brand’s vp of marketing, Bruce Weiss, that meant Trojan’s packaging was also Trojan’s marketing.

"In the earliest days," Weiss said, "the packaging was created to be discreet and communicate the safety and efficacy of the product while also touting the company’s unique manufacturing process."

It was the packaging that contained little brochures that talked about Trojan’s rigorous, machine-based testing. It was the packaging that boasted of the sort of performance a buyer hopes to get from a condom (“As Thin as a Shadow. As Strong as an Ox!”) And, most important, it was the packaging that displayed Trojan’s signature Roman centurion helmet, a memorable brand logo that was also an enduring metaphor of protection, and also conquest.

"The helmet was the element that said that men would be buying these," said Jerry Jankowski, who teaches at the Otis College of Art and Design and runs his own firm, Jankowski Design. "The aggressive aspect, the [suggestion of] conquering, works very well. The Trojans were known for their aggressiveness, that they were going to fight and win."

Indeed, as the photos here show, the evolution of Trojan’s packaging tells the story of condoms themselves and how Americans were persuaded to use them, taught to trust them, and eventually ask for them by name.