Question:
I am looking for the rate for mailing a postcard from the US to Canada in the 1930s

Answer: According to the UPSS US Postal Card Catalog the standard rate forpostal cards from the US to Canada was 1-cent from 1JUL1928 to 1NOV1931when the rate was raised to 2-cents. According to "US International Postal Rates, 1872-1996" by Anthony S.Wawrukiewicz and Henry W. Beecher, the USA post card rate to Canada hadbeen 1c from July 1, 1928, and increased to 2c on September 1, 1931. The"Postal Bulletin" of August 14, 1931 (No. 15678) confirms that September1 is the correct date of the post card rate change to Canada (and alsoto Newfoundland).Note: The USA letter rate to Canada (and Newfoundland) increased from2c to 3c an ounce that same day. At the same time, the USA air mail rateto Canada increased from 5c to 6c for the first ounce.The post card rate to certain other destinations in British Americadid in fact increase from 2c to 3c on November 1, 1931. That is probablythe source of the misinformation in the UPSS catalog.