On October 31, 1864 Nevada became the 36th state to enter the union, and the phrase "Battle Born" on the state flag reflects the state's entry during the American Civil War. It has been celebrated officially since 1939.
In 1999, voters and the state legislature decided that as of 2000 the recognized holiday should be moved to the last Friday of October, citing that it would garner more attention (and more appreciation!) if it was part of a three-day weekend.
Because it's a state holiday, schools, libraries, some banks, and all state offices and institutions are closed. Utilities, the post office and garbage pickup will remain open.