Who or what is responsible for bringing together scarce resources to produce most of the goods and services in the u. s.?

The United States can be called a "mixed" economy, since the government does play a large role, but generally it is a free market, capitalist economy in which firms and households are mostly responsible for managing their scarce resources without government management. Firms (companies) produce most of the goods and services in the U. S., and decide how much to produce based on demand and other constraints. In short, the free market is mostly responsible.