Data from the United States Census Bureau shows fewer people are heading for the sun, as the recession has curbed migration to Florida, Arizona and Nevada. July figures, the most recent data available, show slowdowns in population growth in Tampa, Atlanta, Las Vegas and Phoenix, former magnets for people on the move. Rust-belt metro areas such as Buffalo, N.Y., Pittsburgh and Cleveland stanched some population losses, and Boston, Los Angeles and New York saw gains. Well-to-do exurbs around Washington, D.C., saw growth slowdowns as people weary of costly commutes moved closer to federal jobs in the nation’s capital. A majority of Florida counties saw population declines.