Inter-University Consortium for Political and Social Research provides more than 500,000 digital files containing social science research data. To access data, you must link to the site through Google or Facebook.
Releases from the 2010 census have begun. This can be a complicated site to navigate. Try using American FactFinder as a way of getting started and be prepared to spend some time getting acquainted with it. Ask the reference staff at UW Tacoma Library for assistance.
Locating non-U.S. data
What is collected and how it is collected will depend on the country. This means it might be hard to compare two different areas.
Locate statistical agencies of individual countries. The US Census Bureau has a list which can help you get started.
Locate English versions of country or city websites.
Google Translate can help figure some things out, especially if you just need to read the labels on a table.
More developed countries will usually have more robust statistical agencies and better English language sites
Larger cities might also have their own information pages, which could have some business/economy related statistics to attract businesses (the equivalent of a Chamber of Commerce?). These will likely be in the local language.