What began in 1974 as a one-day tribute to Harlem has evolved over four decades into a monthlong celebration of the community’s rich economic, political and cultural history. Things kick off on July 28 with “A Great Day in Harlem” and reach a fever pitch during the bursting-at-the-seams weekend of events held under the banner of “Summer in the City” and “Harlem Day,” including an auto show, children’s festival, small-business expo, fashion show, educational fair, outdoor film screening and a dancing-in-the-street party.