Another major concern of European-Americans in relation to Chinatowns was the smoking of opium, even though the practice of smoking opium in America long predated Chinese immigration to the United States. Tariff acts of 1832 established opium regulation, and in 1842 opium was taxed at seventy-five cents per pound. In New York, by 1870, opium dens had opened on Baxter and Mott Streets in Manhattan Chinatown, while in San Francisco, by 1876, Chinatown supported over 200 opium dens, each with a capacity of between five and fifteen people. After the Burlingame Commercial Treaty of 1880, only American citizens could legally import opium into the United States, and thus Chinese businessmen had to rely on non-Chinese importers to maintain opium supply. Ultimately, it was European-Americans who were largely responsible for the legal importation and illegal smuggling of opium via the port of San Francisco and the Mexican border, after 1880.