Four foreign source areas produce the heroin available in the United States: South America (Colombia), Mexico, Southeast Asia (principally Burma), and Southwest Asia (principally Afghanistan). However, South America and Mexico supply most of the illicit heroin marketed in the United States. South American heroin is a high-purity powder primarily distributed to metropolitan areas on the East Coast. Heroin powder may vary in color from white to dark brown because of impurities left from the manufacturing process or the presence of additives. Mexican heroin, known as “black tar,” is primarily available in the western United States. The color and consistency of black tar heroin result from the crude processing methods used to illicitly manufacture heroin in Mexico. Black tar heroin may be sticky like roofing tar or hard like coal, and its color may vary from dark brown to black.

Pure heroin is rarely sold on the street. A “bag” (slang for a small unit of heroin sold on the street) currently contains about 30 to 50 milligrams of powder, only a portion of which is heroin. The remainder could be sugar, starch, acetaminophen, procaine, benzocaine, or quinine, or any of numerous cutting agents for heroin. Traditionally, the purity of heroin in a bag ranged from 1 to 10 percent. More recently, heroin purity has ranged from about 10 to 70 percent. Black tar heroin is often sold in chunks weighing about an ounce. Its purity is generally less than South American heroin and it is most frequently smoked, or dissolved, diluted, and injected.