Final answer:
Marijuana was made illegal in the United States in 1937, when Congress passed a federal law banning it.
Step-by-step explanation:
In the early 1900s, an influx of immigrants began entering the country from Mexico. These newcomers took up residence in White communities, spoke a different language, and began competing for jobs and resources. They used marijuana more frequently than most Americans. Police and others began to circulate rumors regarding the substance's link to violence and immorality. Newspapers and lawmakers spoke about the "Marijuana Menace" and the “evil weed," and articles and images began to portray it as a corrupting force on America's youth. Beginning in 1916, state after state began passing laws prohibiting marijuana use, and in 1937 Congress passed a federal law banning it (White 2012). Penalties for its usage increased over time.