The 1950 Census Tract files were originally created by keypunching the data from the printed publications prepared by the Bureau of the Census. The work was done under the direction of Dr. Donald Bogue, whose wife, Elizabeth Mullen Bogue, completed much of the data work. Subsequently, the punchcards were converted to data files and transferred to the National Archive and Records Administration (NARA).
These reports only include tracts. The 1950 Census was released separately for tracts and counties.
Note that County data comes from Michael R. Haines set called "Historical, Demographic, Economic, and Social Data: The United States, 1790-2000" which comes from the printed forms of U.S. Census Bureau, while Tract data comes from Elizabeth Mullen Bogue Files.