american protective association

from The Collaborative International Dictionary of English v.0.48

American Protective Association \A*mer"i*can Pro*tect"ive
As*so`ci*a"tion\
   A secret organization in the United States, formed in Iowa in
   1887, ostensibly for the protection of American institutions
   by keeping Roman Catholics out of public office. Abbrev.
   commonly to A. P .A.
   [Webster 1913 Suppl.]