Defining race, ethnicity, and ancestry is complex and contentious. The U.S. Census revises its definitions every ten years.
The U.S. Census links below help define these categories. And they point to relevant statistics.
Allows you to keyword search for data across many recent censuses. You can try to relate different variables.
NOTE: Copying a URL for a table probably will NOT work. Make sure to copy data to an email message and send it to yourself.