The new downturn rolled back gains in industrial production and employment, prolonged the Depression and caused Roosevelt to increase the work relief rolls of the W.P.

NYTIMES: The Great Depression

The average annual return of the Dow Jones industrial average since the start of the great depression in 1929 was 7.8% under Democratic administrations, against 0.6% for Republican ones.

FORBES: Maybe Tall Democratic Presidents Are Better For Stocks

Businesses failed, industrial production slowed, housebuilding slumped, unemployment soared, the Great Depression began and the repercussions were felt across the world.

BBC: More

The globalisation that followed the industrial revolution was brought to an end by two world wars, high protectionist barriers and the Great Depression.

ECONOMIST: Playing leapfrog