The ancestors of most Bostonians may have hailed from Ireland and Italy, but the current top two immigrant groups are from China and the Dominican Republic, according to City of Neighborhoods: The Changing Face of Boston, an exhibit at the Boston Public Library through August 22. Overall, about 27 percent of city residents were born abroad, a quarter of them in Asia. Nearly half of East Boston’s inhabitants are foreign-born, the majority from Latin and South America. Boston also has the third-largest Haitian population in the country (after New York City and Florida), and a growing Cape Verdean community. These dramatic trends are illustrated through maps, U.S. Census data, photographs, and drawings that make clear that this ever-changing population influences the city’s physical landscapes and culture in countless ways—and always has.