To answer the above question, the relevant sentence is: Although they are still technically legal tender in the United States, high-denomination bills were last printed on December 27, 1945, and officially discontinued on July 14, 1969, by the Federal Reserve System, due to' lack of use'.
This justifies what answer for what question? Q & A:
Passage: Although they are still technically legal tender in the United States, high-denomination bills were last printed on December 27, 1945, and officially discontinued on July 14, 1969, by the Federal Reserve System, due to' lack of use'. The $5,000 and $10,000 effectively disappeared well before then.

Question: Based on this passage, when did they stop making thousand dollar bills?
December 27 , 1945