Online and free through FamilySearch.org (sign-in required):

• 1940 U.S. Census
  
• 1930 U.S. Census
  
• 1920 U.S. Census
  
• 1910 U.S. Census
  
• 1900 U.S. Census
  
• 1880 U.S. Census
  
• 1870 U.S. Census
  
• 1860 U.S. Census
  
• 1850 U.S. Census
  

• Centre Lines uses the version of the 1890 Census which did survive and organizes Centre County's population by surname.
• Online through Penn State's PA's Past: Digital Bookshelf
• At the Pennsylvania Room of the Centre County Library and Historical Museum in Bellefonte
• Re-compiled with an index in 1998 and published as Eleventh Census of the Population of the United States Published by Boroughs and Townships in Connection with a Business Directory of the Same. Available for purchase through the Friends of the Centre County Library and Historical Museum