The American Community Survey (ACS) helps local officials, community leaders, and businesses understand the changes taking place in their communities. It is a premier source for detailed population and housing information about our nation.
The American Community Survey collects data on an ongoing basis, January through December, to provide every community with the information they need to make important decisions. They release new data every year, in the form of estimates, in a variety of tables, tools, and analytical reports.
One good place to start is: Fact Finder.
There's also an introductory video here: Data on a Deadline: Quick Reports and Interactive Maps