6.2 million: Total number of teachers in the United States

3.1 million: Number of elementary and middle school teachers

442,000: Number of preschool and kindergarten teachers

175,000: Number of special education teachers

71 percent: Percentage of teachers who are women

17 percent: Percentage of public elementary and secondary teachers under 30 years old

$44,700: Average annual salary of public elementary and secondary teachers

$84,100: Average annual salary of professors at public colleges

$101,200: Average annual salary of professors at private colleges

Source: U.S. Census Bureau