Americans have consumed an estimated 11 to 14 metric tons of heroin per year since 1993. South American heroin dominates the U.S. heroin market, particularly in the eastern United States Mexican heroin makes up the second largest share, supplying one-quarter of the heroin consumption. The bulk of Mexican heroin is being shipped through and consumed in the Western United States Southeast and Southwest Asia provide the remaining supply of heroin for consumers. The dominance of South American heroin has steadily increased over the last 5 years. The Southeast United States is the preferred import region for South American heroin. The Southeast United States is the primary importation region for all heroin entering the United States. About one quarter of the heroin entering the United States comes through the Northeast United States. The majority of Asian heroin enters the United States through the Northeast region. Slightly less than one quarter of the heroin flow enters the United States through the TexasPlus region. But the flow of South American heroin through this region is increasing. The majority of this heroin is Mexican, but more than a quarter is from South America. Only 11 percent of heroin entering the United States comes through the CaliforniaPlus region. South American heroin dominates the heroin market -- both from a supply and consumption perspective. U.S. law enforcement agencies are seizing, at best, 10 percent of the heroin moving into and through the United States, with the majority of seizures occurring at import. Because the majority of heroin is being shipped into the United States through the Southeast United States and Northeast United States, performance in these regions has a substantial impact on national effectiveness. 11 figures, 10 tables, 3 appendixes