1. On July 15, 1870, the first passenger train arrived in Santa Fe, New Mexico, marking a significant milestone in the state's transportation history. The Atchison, Topeka, and Santa Fe Railroad played a crucial role in the development of the state's economy and culture.

2. In 1945, the world's first nuclear explosion took place at the Trinity Site in southern New Mexico. The top-secret project, known as the Manhattan Project, was a joint effort between the United States and several other countries to build an atomic bomb during World War II.

3. New Mexico became a state on January 6, 1912, but it was not until July 15, 1955, that the state officially adopted its current flag. The design features a red sun symbolizing the state's Native American heritage, a yellow background representing the Spanish influence, and the state seal in the center.

4. On July 15, 1982, a massive flood struck the town of Silver City in southwestern New Mexico, causing widespread damage and claiming the lives of eleven people. The event, known as the Silver City Flood, was caused by heavy rainfall and flash flooding.

5. The historic La Mesilla Plaza in southern New Mexico was the site of a significant Civil War battle on July 15, 1861. The Confederate army, led by General Henry Hopkins Sibley, defeated Union forces and took control of the region. The battle had lasting effects on the state's political and economic landscape.