1940 Census data for Connecticut is available for these geographic areas:
(Note that not all information is available for all geographic levels)
(note, tracts were not established until after 1930 so there are not comparative figures for earlier censuses):
(note, blocks were not established until after 1930 so there are not comparative figures for earlier censuses):
From the U.S. Census Bureau site (posted on several pages for historic censuses):
"A Note on Language
Census statistics date back to 1790 and reflect the growth and change of the United States. Past census reports contain some terms that today’s readers may consider obsolete and inappropriate. As part of our goal to be open and transparent with the public, we are improving access to all Census Bureau original publications and statistics, which serve as a guide to the nation's history."