1. On July 21, 1821, New Mexico officially became a territory of Mexico after gaining independence from Spain. This date is celebrated as New Mexico's official Founders' Day.

2. In 1865, a group of Apaches attacked Fort Stanton, which was being used as a military hospital during the Civil War. The attack resulted in the deaths of several soldiers and civilians and marked a significant moment in the history of conflict between Native Americans and white settlers in the region.

3. On July 21, 1877, William H. Bonney, also known as Billy the Kid, was arrested for the first time in New Mexico. Bonney would go on to become one of the most infamous outlaws in American history, and his legacy still looms large in the state.

4. In 1945, the world's first atomic bomb was tested at Alamogordo, New Mexico. The event, known as the Trinity Test, marked a major moment in the history of science and technology, but it also had profound and devastating implications for the people living in the surrounding area and for the world as a whole.

5. On July 21, 2015, New Mexico Governor Susana Martinez announced that she would be seeking the Republican nomination for President in the 2016 election. Martinez ultimately decided not to run, but her candidacy briefly captured national attention and highlighted the growing political importance of Latino voters in the United States.