From Silver Monthly
''The effects of inflation, coupled with the strong incentives for private
collection of the silver coinage which had now been demonetized, caused
silver coins to quickly disappear from circulation. By 1970, strictly
cupronickel coinage was manufactured and circulated by the U.S.
government. The underlying circumstance which made the Coinage Act of
1965 necessary was the inflation caused by increases in the money
supply. True enough, the strain on the nation’s supply of silver at the
time was great, due in part to the government’s interference in prices.''