In 1968, Congress first designated the week including September 15 and 16 as National Hispanic Heritage Week. This week was chosen because of two historical events: Independence Day (Sept. 15), which celebrates the formal signing of the Act of Independence of Central America in 1821; and Mexico's Independence Day (Sept. 16), which commemorates the beginning of the struggle against Spanish control in 1810. In 1988, Congress expanded the week to a full 31-day period.