(Reuters) - U.S. President-elect Donald Trump has nominated Ben Carson, a retired neurosurgeon who made a failed bid for the Republican presidential nomination, to oversee the federal Department of Housing and Urban Development. Referred to as HUD, the agency had a budget of $48 billion in 2016 and is best known for the administration of public housing - historically large buildings where poor people are able to obtain low-cost homes. Large-scale public housing in the country’s largest urban areas still houses millions of people. In the past few decades, the federal government, in partnership with local governments, has largely abandoned large-scale public housing buildings and instead supported mixed-income projects and the use of vouchers, commonly known as “Section 8,” to help low-income people rent from commercial properties.     The largest budget allocations for HUD are for public housing and other assistance programs for groups including Native Americans, the elderly and disabled people. Together, those programs are budgeted for roughly $40 billion. Other responsibilities of the agency include: 