We identify the economic interests in the United States that have a partisan alignment. We disaggregate corporate and trade association political action committees by economic sector, using the most fine-grained classifications available. We then analyze the campaign contributions to House incumbents from each sector, controlling for the majority party, economic geography, committee membership, and electoral competition. We find wide variation in how economic sectors relate to the parties. More than one third have a clear party tilt, with far more leaning toward Republicans than to Democrats. The remainder have no discernible partisan preference, either giving without reference to party or opportunistically to the majority. Republican-leaning sectors concentrate in particular enterprises, especially natural resources extraction, while most professional service sectors are nonpartisan. Business is not a monolith, to be contrasted with "labor" or "ideological interest groups," but embedded in economic sectors that are more or less politicized in partisan terms.