Marijuana use can be traced as far back as the Neolithic era (8,000-5,000 BC), where charred remains of cannabis seeds have been unearthed in ancient braziers of present day Romania.

Both George Washington and Thomas Jefferson were known to grow Cannabis on their plantations in the 1700s, most likely for the production of hemp.

THC, or tetrahydrocannabinol, is the principal psychoactive ingredient in cannabis. The potency of THC in marijuana determines the strength of the substance.

THC is stored in fatty tissues in the body, including the brain.
The most potent form of marijuana is called sinsimilla, and is produced by preventing the female plant from being pollinated. This keeps the plant seedless to produce a high resin content, allowing for a higher content of THC.

Medicinal marijuana is currently legal in 12 states: California, Rhode Island, Vermont, New Mexico, Nevada, Montana, Colorado, Maine, Oregon, Alaska, Hawaii and Washington State. However, According to federal law, marijuana use is illegal regardless of whether it's used medicinally.
Marijuana is used medicinally to fight chronic pain, spasticity from multiple sclerosis, nausea and vomiting in HIV patients, as well as the nausea and vomiting associated with chemotherapy.

According to the Department of Justice, the principle source of foreign-produced marijuana in the U.S. is from Mexico. However, production appears also to be on the rise in Canada and domestically in the U.S.
According to the FBI, 800,000 people were arrested on marijuana charges in 2006 in the United States. Nearly 90% of these arrests were for marijuana possession.

A 2006 survey reported that marijuana usage among males was twice as high than among females of the same age groups.

According to the Office of National Drug Control Policy, marijuana is the most commonly used illicit drug in America.