The New Museum opened an $82 million expansion this week, starting a new chapter for the postwar contemporary art museum on New York’s Lower East Side — and turning a page on an important era for New York’s art world.

Over the last 20 years New York’s art institutions have been in growth mode. The Museum of Modern Art and Whitney Museum of American Art both opened major expansions. Right on their heels were New York’s mega-dealers: The biggest commercial art galleries got really big, opening warehouse-sized galleries that rival all but the largest museums, at least in terms of space.