⛓️ Why Did the Boom Happen? — Connected Causation
The boom was not caused by any single factor. What made it so powerful was that several causes reinforced each other. This is what examiners mean when they say "show how causes connect":
WW1 (1914–1918) created industrial capacity — While European factories were destroyed by war, American factories were built up to supply Allied forces with weapons, food and equipment. By 1918, the USA had the most modern industrial base in the world. This is where the boom's foundations were laid.
Mass production (from 1908) made goods affordable — Henry Ford's moving assembly line at Highland Park meant a Model T took 93 minutes to build instead of 12 hours. The price fell from $850 (1908) to $290 (1925). This led to a consumer revolution: ordinary workers could buy cars, not just the wealthy.
Republican "laissez-faire" policies kept business free — Presidents Harding, Coolidge and Hoover refused to interfere in business. Treasury Secretary Andrew Mellon slashed the top income tax rate from 73% to 25%, leaving wealthy investors with more money to reinvest. The Fordney-McCumber Tariff (1922) blocked cheap foreign imports, protecting American manufacturers.
Credit turned "want" into "purchase" — Hire purchase (paying in weekly instalments) meant that even if a family couldn't afford a $290 Model T outright, they could buy one for a small deposit. By 1929, 60% of cars and 80% of radios were bought on credit. This massively expanded the pool of consumers — but it also built up dangerous levels of debt.
Advertising created demand for goods people didn't know they needed — By 1929, American companies spent $3 billion a year on advertising. Radio, cinema and billboards reached millions of people simultaneously, telling them that refrigerators, vacuum cleaners and silk stockings were essential — not luxuries. This kept demand high even as factories produced more and more goods.
= A self-reinforcing "virtuous cycle" — More production meant lower prices. Lower prices meant more buyers. More buyers meant more factory jobs. More jobs meant more wages. More wages meant more buying. Each factor fed the next. This is why the boom lasted nearly a decade — but it also explains why, when confidence broke in 1929, the whole cycle went into reverse.
The key exam skill is showing that no single cause explains the boom on its own. Mass production without credit would have left goods unaffordable. Credit without mass production would have created debt with nothing to buy. Republican policies created the CONDITIONS for the boom; WW1 gave America the CAPACITY; and advertising and credit gave ordinary Americans the ABILITY and DESIRE to participate.
