Security was extra tight at Maryland’s Andrews Air Force Base on April 16, 1972, as a pair of high-profile Chinese emissaries disembarked from a military plane. Government officials whisked the envoys into waiting vehicles that sped off with a police escort through the streets of Washington, D.C. The foreign arrivals weren’t destined for the White House or the State Department, however, but the National Zoo.

The diplomats—a pair of 18-month-old giant pandas named Ling-Ling and Hsing-Hsing—had been given to the United States as symbols of friendship during Richard Nixon’s historic presidential visit to the People’s Republic of China in February 1972 that normalized relations between the two countries. The gift of the placid, black-and-white bears was part of China’s long-standing tradition of “panda diplomacy” that began during the seventh-century Tang Dynasty when Empress Wu sent a pair of pandas to the Japanese emperor.

News of the cuddly gifts created a sensation in America as zoos from the Bronx to San Diego fiercely lobbied the White House to become the pandas’ new home. The exuberant reaction was a far cry from 1958 when the United States denied entry to a panda bound for Chicago’s Brookfield Zoo because she was “a product of Communist China.”

In early March, the president and first lady Pat Nixon decided that the Smithsonian’s National Zoo would be the pandas’ home. The decision was so eagerly awaited that Nixon personally called the editor of the Washington Star, Crosby Noyes, with the scoop. The president also broke the news that the pair would include one female and one male, but that their arrival would be delayed so that they could receive a crash course in the birds and the bees by watching other pandas mate at the Beijing Zoo. “The problem with pandas is they don’t know how to mate,” Nixon explained over the phone to Noyes.

Nixon knew the arrival of the pandas could be a public relations coup. “I could imagine that that zoo will get the biggest play in history,” he told Noyes. The National Zoo declared April 20, 1972, to be “Panda Day” as it debuted the Chinese bears. Nixon made sure that the first lady was there for the occasion. “It’s gonna be a hell of a story,” he told her in a recorded phone conversation, and he was right.

Twenty thousand people came to see the pandas as photographers snapped away. Ling-Ling delighted the crowds by licking her porridge bowl clean and putting it on her head. That afternoon, Nixon called his wife to “see how the panda thing went.” “They were just darling. Everybody raved about them,” she told her husband, who was curious if Mrs. Nixon had pet the pandas and wanted to know how the media covered the event. “Did they get a good picture of them, I hope?” he asked.

He needn’t have worried about the media reaction. “New Pandas Melt Hearts at National Zoo,” declared The New York Times. The following Sunday, 75,000 people thronged the zoo and waited in a quarter-mile-long line to catch a glimpse of America’s newest celebrities, who graced magazine covers and proved to be an economic boon for producers of toys and stuffed animals.

The following year, the zoo’s stars moved into an air-conditioned “panda palace” with private sleeping dens and an expansive terraced area that was kept at 50 degrees to replicate their native climate. The lavish digs raised hackles that the pandas were living “like mandarins at U.S. taxpayer expense,” but no amount of bad press could sour the American public on the pandas, who continued to be the National Zoo’s top attraction until Ling-Ling died in 1992 followed by Hsing-Hsing seven years later. The pair produced five cubs, but none survived more than a few days. The Panda House remained empty until the arrival of Mei Xiang and Tian Tian in 2000. Their first cub, Tai Shan, returned to China in 2010, and last August Mei Xiang gave birth to a girl cub named Bao Bao.

Largely forgotten today is that before China gifted the pandas during Nixon’s 1972 trip, the White House had announced an animal offering of its own, although selecting the right beasts was not an easy task for American diplomats. Bald eagles and mountain lions were considered too belligerent, the grizzly bear was co-opted by the Soviet Union and the Beijing Zoo already had a bison. With their choices limited, the diplomats finally settled on their gift to the people of China—a pair of musk oxen.

Before returning home with the giant pandas, National Zoo Director Theodore Reed formally presented the musk oxen—Milton and Mathilda—who had been purchased from the San Francisco Zoo. It’s safe to say the shaggy beasts did not spark the same sensation in China as the pandas did in America. Upon arrival, Milton suffered from postnasal drip, coughing spells and a skin disease that was causing his hair to fall out in clumps. Mathilda was in rough shape as well. “One can only hope that a century from now ‘musk ox’ will not be Chinese slang for a useless object that can’t be disposed of,” commented a New York Times editorial.

Even Reed knew the United States got the better of the deal. “Frankly, I just don’t think musk oxen have the sex appeal pandas do,” Reed cooed after the arrival of Ling-Ling and Hsing-Hsing. “You like musk oxen, but pandas can steal your heart away.”

A couple of months later, Madame Sun Yat-sen, vice chairman of the Chinese government, was dining with a New York Times reporter. She took out her panda-decorated cigarette case, which led her to lament on the recent animal swap, “We got a bad deal. That’s Nixon for you.”