This government Web site contains census data going back to 1790, but not necessarily the census in its entirety. All documents are in a PDF format.
U.S. government census data grouped into categories such as people, business, geography, and others. Data files are available as well as prepared tables.
American FactFinder provides access to data about the United States, Puerto Rico and the Island Areas. The data in American FactFinder come from several censuses and surveys. THIS PUBLIC DATABASE ONLY HAS DATA BACK TO 2002. You can look here for the 2016 estimated population for your cities from the American Community Survey.
Begin looking for number of population and manufacturing jobs in the COUNTY DATA BOOK for 1940. It is located in the Government Documents stacks, under the Superintendent of Documents number: C3.134/2:C83/947. You will find other editions nearby.
You will also find other editions in both the Waldo Library general stacks (2nd floor) and the MOST recent editions in the Reference Desk Collection on the 1st floor of Waldo Library, under the call number HA 202 .A36.
YOU MAY NEED TO LOOK IN BOTH LOCATIONS.
Most census volumes from 1890 to 1970 are available in Waldo Library general stacks (2nd floor) under the call number HA 201.
Printed census volumes for the years 1980 to 2000 are available in the Government Documents Department of Waldo Library, 2nd floor.