Captain America Comics #1, which went on sale December 20, 1940 (a year before the attack on Pearl Harbor, but a full year into World War II), showed Cap on the front cover punching Nazi leader Adolf Hitler. It sold nearly one million copies.

The average retail price of gas in 1940 was $0.18 per gallon, which is equivalent to about $3.35 per gallon today.

The Roswell UFO incident, which involved a United States Army Air Forces balloon crash at a ranch near Roswell, New Mexico, has been described as "the world's most famous, most exhaustively investigated, and most thoroughly debunked UFO claim."

Because it happened without a declaration of war and without explicit warning, the attack on Pearl Harbor led U.S. President Franklin D. Roosevelt to proclaim December 7, 1941, "a date which will live in infamy". It also led to the United States' formal entry into World War II the very next day.

On July 16, 1945, the Allied Manhattan Project successfully detonated an atomic bomb in the New Mexico desert and by August had produced atomic weapons based on two alternate designs.

In the summer of 1946, Western Europeans enjoyed their first war-free summer in years, and two French designers sought to deliver fashions that matched the liberated mood of the people. Jacques Heim designed a two-piece swimsuit that he called the atome, after the smallest known particle of matter, promoting it as the "world's smallest bathing suit." Louis Réard launched an even smaller design named after the Bikini Atoll, where the first public test of a nuclear bomb had taken place. The skimpy suit was considered so risqué that no runway model would wear it, but his bikini quickly spread to beaches everywhere after he hired a dancer from the Casino de Paris to model it.

Although technically preceded by Enzo Ferrari's Auto Avio Costruzioni 815 of 1940, the 125 S was the first vehicle to bear the Ferrari name when it debuted on May 11, 1947, at the Piacenza racing circuit. Although it was unable to finish that first race, the 125 S would go on to win six of its fourteen races in 1947.

Although It's a Wonderful Life initially received mixed reviews, it was nominated for five Academy Awards, including Best Picture, and has since become a Christmas classic.

The first multimedia star, Bing Crosby was one of the most popular and influential musical artists of the 20th century. He was a leader in record sales, radio ratings, and motion picture grosses from 1930 to 1954, and led all artists during the 1940s with nine No. 1 singles. The biggest hit of Crosby's career was his recording of Irving Berlin's "White Christmas," which he introduced on a Christmas Day radio broadcast in 1941. It would go on to become the best-selling single of all time, but Crosby was dismissive of his role in the song's success, saying "a jackdaw with a cleft palate could have sung it successfully".

When the Brooklyn Dodgers signed Jackie Robinson in 1941, it heralded the end of racial segregation in professional baseball that had relegated black players to the Negro leagues since the 1880s. During his 10-year MLB career, Robinson won the inaugural Rookie of the Year Award in 1947, was an All-Star for six consecutive seasons from 1949 through 1954, and won the National League Most Valuable Player Award in 1949--the first black player so honored. He also played in six World Series, contributing to the Dodgers' 1955 World Series championship, and was inducted into the Baseball Hall of Fame in 1962.