The main effect that the use of credit had on the economy in the 1920s is that it allowed people to make poor and risky investment decisions that led to a great amount of over-valuation of stocks.
This led to the Great Crash in 1929.
Step-by-step explanation:
The effect is overproduction, too many credit purchases, stock speculation.
The period from 1920-29 is usually referred to as the 'Roaring Twenties' as a result of it had been a time of noise, spirited action and economic prosperity. the primary warfare had been sensible for yankee business. plant production had up sharply to fulfill the wants of the war