Investors should follow the path of the strongest job and population growth. : In the U.S., 24-hour cities—the cities that essentially are up all night—translate mainly to the coastal gateway cities: Boston, Los Angeles, New York, San Francisco, and Washington, D.C. Meanwhile, 18-hour cities are often the markets with above-average urban population growth, plus a lower cost of living and lower cost of doing business relative to 24-hour cities.