The last day of March.

The last day of march marks the end of the first quarter (Q1) of the year. It is also known as World Backup Day, a day dedicated to raising awareness about the importance of backing up your data and files. Additionally, it is the birthday of the famous Dutch painter Vincent van Gogh. In some parts of the world, it is celebrated as National Crayon Day, a day dedicated to recognizing and appreciating the history and significance of crayons.

In the United States, March 31 is also recognized as Cesar Chavez Day, a state holiday in California, Colorado, and Texas. It commemorates the life and achievements of Cesar Chavez, a civil rights and labor activist who co-founded the United Farm Workers (UFW) and worked to improve the working conditions of migrant farm workers.

March 31 is also associated with several historic events, including the completion of the Eiffel Tower in 1889, the resignation of US President Richard Nixon in 1974, and the launch of the world's first online service, CompuServe, in 1979.

In terms of astrology, March 31 falls under the zodiac sign of Aries, which is associated with courage, leadership, and independence. People born on this day are thought to share these qualities and maybe adventurous, energetic, and proactive in their personal and professional lives.