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The economic boom in America in the 1920's was a result of the impact of WWI, natural resources, advances, production, advertising & salesmanship, ease of and Republican policies. Mass production involved and lines, improving efficiency in industries. This and technological advances greatly relate to the growing industry. WWI gave US firms less and more markets to trade with. Ease of credit allowed ordinary Americans to afford what were once 'luxury' items. Republican policies such as l-f, low taxes, and policies relating to unions, allowed for relaxed and more money in circulation within the US.