In 1968, Shirley Chisholm became the first black woman elected to the United States Congress, representing New York's 12th congressional district for seven terms from 1969 to 1983.

Operated by Central Overland California and Pikes Peak Express Company, the Pony Express was of great financial importance to the U.S. During its 18 months of operation, reducing the time for messages to travel between the Atlantic and Pacific coasts to about 10 days. It was not a financial success, however, and went bankrupt when faster telegraph service was established.

12-year-old Calvin Graham lied about his age when he enlisted in the U.S. Navy in 1942. His real age wasn't discovered until after he was wounded in the Naval Battle of Guadalcanal.

Barack Obama served as the 44th president of the United States from 2009 to 2017. He was born to an American mother of European descent and an African father from Kenya. Obama was born in Honolulu, Hawaii, making him the first president not born in the contiguous United States.

From 1951 to 1992, as part of the nuclear arms race, a swath of land about 65 miles northwest of Las Vegas, Nevada was used for hundreds of nuclear weapons tests.

President James Monroe first stated the Monroe Doctrine during his seventh annual State of the Union Address to Congress. It stated that further efforts by European nations to take control of any independent state in North or South America would be viewed as "the manifestation of an unfriendly disposition toward the United States."

The Tuskegee Airmen were a group of primarily African-American military pilots who fought in World War II. In all, 992 pilots were trained in Tuskegee, Alabama from 1941 to 1946. Contrary to negative predictions from some quarters, the Tuskegee Airmen were some of the best pilots in the U.S. Army due to a combination of pre-war experience and the personal drive of those accepted for training, and after segregation in the military was ended in 1948 by President Harry S. Truman, the veteran Tuskegee Airmen found themselves in high demand throughout the newly formed United States Air Force.

When Alaska and Hawaii were being considered for statehood in the 1950s, more than 1,500 designs were submitted to President Dwight D. Eisenhower. Of these proposals, one created by 17-year-old Robert G. Heft in 1958 as a school project received the most publicity. His mother was a seamstress, but refused to do any of the work for him. He originally received a B- for the project. After discussing the grade with his teacher, it was agreed that if the flag was accepted by Congress, the grade would be reconsidered. Heft's flag design was chosen and adopted by presidential proclamation in 1959. Heft's teacher kept their agreement and changed his grade to an A.