When did D.C. make its fabled transition from sleepy Southern town to vibrant modern city? Ask a dozen locals and you’ll get a dozen answers—all of them dating to right around the time the person who’s talking arrived here. No surprise, then, that retired Postie Chalmers Roberts and architect Charles Cassell remember the 1930s as modern D.C.’s time of emergence: That’s when Roberts moved here, and it’s when District native Cassell came of age. Funny, my parents always said D.C. grew up with the Great Society. And lately, I’ve felt like telling newcomers that the city really became its current self during Reagan’s second term—when I started high school. Match your recollections against the oldtimers’, who’ll be chatting with storyteller Sherry Geyelin at “Washington in Black and White,” an evening of oral recollections of D.C. in the ’30s and ’40s, at 3 p.m. at the Historical Society of Washington, D.C., 1307 New Hampshire Ave. NW. $5. (301) 891-1129. (Michael Schaffer)