The two Giant Pandas, Hsing-Hsing and Ling-Ling, arrived at Andrews Air Force Base at 5 a.m. and were transported to the National Zoological Park. A month before on March 13th, President Richard Nixon announced that the pandas would reside at the National Zoo, and called them a "gift from all the people of China to all the people of the United States." On April 20, the pandas were officially presented, with Mrs. Nixon and members of Congress in attendance. With a rate of approximately 1,200 people per hour, nearly 24,000 visitors came to see Hsing-Hsing and Ling-Ling on their first weekend. More - https://siarchives.si.edu/collections/siris_sic_1003.