BALTIMORE - For more than three decades, the Tyson family has assembled on Preakness day at Grandma Lillie's brick rowhouse near the Pimlico racetrack for an annual moneymaking ritual: renting space for visitors' cars, selling burgers and hot dogs, and sometimes allowing a familiar face inside to use the bathroom.

Can a city survive if its population shrinks by almost a third within a generation? This is a question hanging over Venice, where tourism, overcrowding and sky-high living costs are pushing out more and more residents.