The Great Depression in the United Kingdom, also known as the Great Slump, was a period of national economic downturn in the 1930s, which had its origins in the global Great Depression. It was Britain's largest and most profound economic depression of the 20th century. The Great Depression originated in the United States in late 1929 and quickly spread to the world. Britain did not experience the boom that had characterized the U.S., Germany, Canada and Australia in the 1920s, so its effect appeared less severe. Britain's world trade fell by half (1929–33), the output of heavy industry fell by a third, employment profits plunged in nearly all sectors. At the depth in summer 1932, registered unemployed numbered 3.5 million, and many more had only part-time employment.