"Until 1913 marijuana was legal throughout the United States under both state and federal law. Beginning with California in 1913 and Utah in 1914, however, states began outlawing marijuana, and by 1930, 30 states had adopted marijuana prohibition. Those state-level prohibitions stemmed largely from anti-immigrant sentiment and in particular racial prejudice against Mexican migrant workers, who were often associated with use of the drug. Prohibition advocates attributed terrible crimes to marijuana and the Mexicans who smoked it, creating a stigma around marijuana and its purported “vices.”"
One century later, the prejudices haven't changed.