The U.S. Census Bureau currently estimates the country's population to be 321,813,000. The U.S. population almost quadrupled during the 20th century, from about 76 million in 1900. The third most populous nation in the world, after China and India, the United States is the only major industrialized nation in which large population increases are projected. In the 1800s the average woman had 7.04 children, by the 1900s this number had decreased to 3.56.
The United States has a very diverse population; 37 ancestry groups have more than one million members. German Americans are the largest ethnic group (more than 50 million)followed by Irish Americans (circa 37 million), Mexican Americans (circa 31 million) and English Americans (circa 28 million).
White Americans are the largest racial group; Black Americans are the nation's largest racial minority (note that in the U.S. Census, Hispanic and Latino Americans are counted as an ethnic group, not a racial group), and third largest ancestry group. Asian Americans are the country's second largest racial minority; the three largest Asian American ethnic groups are Chinese Americans, Filipino Americans, and Indian Americans.