WHEN THE WHITE HOUSE greeted German Chancellor Angela Merkel last June, Michelle Obama wore Naeem Khan, one of couture’s bold-faced names. Meanwhile, the high-ranking US diplomat overseeing the formal affair wore … a dress snagged from a Southeast Portland vintage shop. How did this happen? Liz Gross, 37-year-old owner of Xtabay, helps explain the life and times of one silk dress.

CIRCA 1962 A shantung silk evening gown is made in Hong Kong; the British colony is a thriving source for knockoffs of Mad Men–era high fashion. “This dress is almost exactly like one Jackie Kennedy dress,” says Gross. “Hong Kong manufacturers would replicate dresses Oleg Cassini and Givency designed for her. This one was probably sold at a high-end department store like Nieman Marcus.”

CIRCA 1960S–’80S The dress makes its way to the wardrobe of Isla Small, who worked for Ford. As private secretary to Lee Iacocca, the company’s legendary president, “She would have attended a lot of formal events and dressed up a lot,” Gross notes.

2001 Gross starts Xtabay as a humble shop on SE Clinton Street. In the early days, her business consists almost entirely of local vintage hounds. But by …

2008 Gross reconfigures to focus on high-end and bridal business. Photos posted to Facebook draw a growing national clientele.

WINTER 2011 In January, Carrie Brownstein wears “Xtabay, head to tail” to the comedy show Portlandia’s New York premiere. In February, Brownstein tells People magazine that Xtabay is one of her “three favorite” places in Portland.

SPRING 2011 Capricia Marshall, Chief of Protocol for the United States, calls from Washington, DC. “I had no idea who she was,” Gross says. “She’d seen People.” Marshall buys the shantung dress and a 1950s cotton dress she’d seen online. “Then I Googled her and was like, ‘Whoa, this is good,’” Gross says. Marshall (who’s technically an ambassador) wears the ’50s dress in Brazil during President Obama’s Latin America tour.

JUNE 2011 Marshall sports the shantung dress alongside the Obamas during Merkel’s gala visit. “She said she got a lot of compliments,” Gross says.