The Internet Archive provides free access to images of the 1920 census. These are not indexed and cannot be searched by name, but can be browsed by enumeration district.
To determine the correct 1920 census enumeration district for the area you wish to search, try this online tool, Obtaining EDs for the (1900-1940) Census in One Step (Large Cities). This page has links to additional tools to search for the descriptions of enumeration districts in smaller areas.
Many local libraries offer free home access (through their websites) to Heritage Quest, which has searchable images of the 1920 census.
