HEROIN TRADE IS SIMPLY ONE OF MANY FLOURISHING CONTRABAND MARKETS THAT ARE COMMONPLACE THROUGHOUT LATIN AMERICA. ACCORDING TO THE DRUG ENFORCEMENT ADMINISTRATION (DEA) WITHIN THE DEPARTMENT OF JUSTICE, MEXICAN HEROIN ACCOUNTED FOR 89 PERCENT OF U.S. SUPPLIES IN 1975. U.S. GOVERNMENT ESTIMATES OF MEXICO'S 1976 MET OPIUM YIELD RANAGED FROM 40 TO OVER 100 TONS. THERE ARE THREE MAJOR AIR AND GROUND ROUTES FOR SMUGGLING HEROIN FROM MEXICO INTO THE UNITED STATES: NORTHEAST TO TEXAS MARKETS, CHICAGO, ILL., AND DETROIT, MICH., NORTH TOWARD EL PASO, TEX., AND DENVER, COLO.; AND NORTHWEST TOWARD SAN DIEGO AND LOS ANGELES, CALIF., AND PHOENIX, ARIZ. LITTLE PROGRESS CAN BE EXPECTED IN LIMITING HEROIN SMUGGLING. THE FACT THAT MILLIONS OF KILOGRAMS OF MEXICAN MARIJUANA ARE SMUGGLED INTO THE UNITED STATES ANNUALLY SUGGESTS THAT CUSTOMS OPERATIONS WILL HAVE ONLY A MINOR IMPACT ON HEROIN SMUGGLING, A PURSUIT FAR EASIER AND MORE PROFITABLE THAN MARIJUANA SMUGGLING. POVERTY IN THE MEXICAN COUNTRYSIDE, THE U.S. GOVERNMENT'S LACK OF CONTROL IN POPPY-GROWING STATES, CORRUPTION, THE PROXIMITY OF THE LUCRATIVE U.S. MARKET, AND POTENTIAL PROFITS CREATE IDEAL CONDITIONS FOR ILLICIT HEROIN TRADE IN MEXICO. MANY OF THESE CONDITIONS ALSO EXIST IN CENTRAL AMERICA AND SOUTH AMERICA. THE DEA HAS TAKEN STEPS TO CONTROL HEROIN TRADE IN LATIN AMERICA AND UNQUESTIONABLY, THE EXTRALEGAL SYSTEM OF ENFORCEMENT (TORTURE, KIDNAPPING, AND SUSPENSION OF CIVIL LIBERTIES) IS RESPONSIBLE FOR DESTROYING THE FRENCH-CORSICAN AND ITALIAN-MAFIA HEROIN TRANSSHIPMENT TRADE IN CENTRAL AMERICA, DOMESTIC DISTRIBUTORS MAY HAVE GREATER OPPORTUNITIES WITH THE ELIMINATION OF FRENCH-CORSICAN AND ITALIAN-MAFIA DISTRIBUTORS AND THE UNITED STATES WILL THEN BE FORCED TO CHOOSE BETWEEN COMPETING INTERESTS OF EFFECTIVE NARCOTICS ENFORCEMENT AND FOREIGN POLICY. TRADITIONALLY, THE LATTER HAS PREVAILED. NOTES AND REFERENCES ARE INCLUDED. (DEP)