Overall nighttime crime incidents in four test areas in Washington, DC, have dropped approximately 50% during the 24-month period following the installation of high-pressure sodium lights. However, although 2187 new lights were added and 18,500 existing luminaires converted to high-pressure sodium by the end of 1973, energy consumption was reduced by 222,000 kilowatt-hours, while the lumen output was increased by 500,000,000.