New York City has one of the world’s biggest subway systems, but some areas of the city are poorly served. While better bus service has helped, there are still large parts of the city, including low-income neighborhoods dependent on public transportation, that are out of reach of any transit. Building new subway lines or line extensions in the South Bronx, southeast Brooklyn. and eastern Queens would reduce travel times and fully connect these communities to the city’s transit system—and thereby job opportunities.