Since the agricultural biotechnology industry in the United States held its first field trials, federal and state governments and private corporations have spent billions of dollars on research, commercial development and regulation. So far, more than 40 genetically modified crops are currently allowed commerce in the United States. These modified crops have two traits — herbicide tolerance (HT) and insect resistance (Bt) — that have been engineered into four commodity crops (corn, cotton, soybeans and canola) that lead the marketplace. Companies that market and produce these crops include Bayer, Monsanto, Dupont/Pioneer, Syngenta and Dow/Mycogen.