As encouraging as it is to see the downtown revival take flight with refurbished theaters, new restaurants, and lofts, the one area that’s sadly missing in the comeback is retail. For younger generations who equate shopping with a mall, it would be a stunning revelation to learn that downtown Detroit was a bustling retailing hub, its streets jammed with shoppers. Or, as Michael Hauser and Marianne Weldon write in their captivating new book, 20th-Century Retailing in Detroit (Arcadia Publishing, $21.99), “the equivalent of four Somerset Collection malls could fit into the amount of space that was formerly devoted to retail shopping downtown.” Hauser and Weldon have assembled a handsome volume packed with photos sure to evoke a tidal wave of memories among Detroiters of a certain age, particularly around the holidays, when downtown Detroit pulsated with activity. The authors devote separate chapters to the big three department stores — Hudson’s, Crowley’s, and Kern’s — as well as sections on specialty stores like Kline’s, Capper & Capper, and Himelhoch’s, and budget retailers, such as Woolworth, Kresge, and Sam’s. There’s also much attention devoted to the Central Business District Association’s (CBDA) efforts (led by the creative spark of Diane Edgecomb) to attract more shoppers downtown as suburban shopping malls grew. But best of all for this season, there’s a chapter on CBDA holiday events. Let the nostalgia snowball.