Type your search term followed by site:.gov
This will limit a search result to government sites only.
For example:
1940 census site:.gov
This will give you a direct link to this census for information.
FamilySearch is a free genealogy organization operated by The Church of Jesus Christ of Latter-day Saints (also known as the LDS Church). It was previously known as the Genealogical Society of Utah (or "GSU") and is the largest genealogy organization in the world. FamilySearch maintains a collection of records, resources, and services designed to help people learn more about their family history. FamilySearch gathers, preserves, and shares genealogical records worldwide. It offers free access to its resources and service online at FamilySearch.org, one of the most heavily used genealogy sites on the Internet. In addition, FamilySearch offers personal assistance at more than 4,500 family history centers in 70 countries, including the Family History Library in Salt Lake City, Utah.
Ancestry is a paid self-services for investigating your genealogy.