Several States in the U.S. Celebrate an Independence Day or Statehood Day when the state became independent from another country and/or joined the Union and became part of the U.S.
California Admission Day celebrates California becoming the 31st state in the Union on September 9th 1850. Today it is a legal state holiday, although most businesses and schools do not close. Some businesses around the state may have special events to commemorate the holiday.