The Statistical Abstract of the U.S. includes brief statistics on almost every topic. The focus is on the U.S. but some international statistics are included. This is a great source to start with to find which agency or organization has collected more in-depth statistics.
Search USA.gov searches .gov, .mil, .us and selected other domains that include official local, regional, state and federal government agencies. This is a good place to search for statistics since the government collects so many statistics on a variety of topics. NOTE: Does not search local government websites using .com domains such as St. Louis County.