The short answer is your idea of how things work in the US is incorrect. Building a bridge certainly doesn't require an act of Congress. Explaining transportati

The short answer is your idea of how things work in the US is incorrect. Building a bridge certainly doesn't require an act of Congress. Explaining transportation funding in the US is complicated because the responsibility for road building is mostly a state and local government issue and there is a variety of systems from state to state. Federal funding to help states usually involves two methods. The first is transportation block grants where the federal government gives states money to use towards transportation at their discretion within certain constraints. The other is funding for specific projects. This funding generally involves the state applying to the federal department of transportation for funds toward a specific project. The department of transportation provides these funds out of a pool of money allocated by Congress each year. Congress plays no formal role in how these funds are disbursed. The department of transportation decides using defined set of criteria. In the past Congress would sometimes earmark funds toward specific projects. This is rare these days as most earmarking of funds is against current congressional rules.