- The Green Book is the Official Directory of the City of New York, published annually by the Department of Citywide Administrative Services (DCAS). It lists contact and descriptive information on City, State, Federal government; local county offices; the court system and foreign consulates. The first Green Book was published in 1918 under Mayor John Hylan, New York City's 96th Mayor.
- From the mid-40s to the early 60s, The Green Book featured the traditional green color but with a velvet cover.
- The first books were pocket sized approximately 2 5/8” x 5 1/4”. Over time they grew in size to the larger, easier-easier-to read version, 3 5/8” x 7 3/8”, which began with the 1992/93 edition.
- The Green Book has been published every year since its inception except in 1945 during a nationwide shortage of paper, every other year in the 1970s due to a national fiscal crisis, and there was a three year gap from 2009 until 2012.
- The directory was always commonly referred to as "The Green Book" due to the cover's color but only officially became the directory’s title in 1984.
- Traditionally covers included an imprint of the City Seal and the name of the current mayor, however in the mid-80s line art depicting events of the time was introduced. More recent covers included the Major League Baseball trophy, several renderings of the Statue of Liberty, a saffron (orange) cover in tribute to The Gates, the work by Christo and Jeanne-Claude that adorned Central Park in 2005 And a 4/color cover with Birdie the GreeNYC mascot. The last section of the Green Book “Factual Highlights” includes a chronological history of New York City, population breakdown by boroughs, number of registered voters, and the assessed valuation of taxable real estate in New York City.
- The Name Index includes the name of every NYC employee listed in the directory.
- The print edition of the Green Book is available for purchase exclusively from the CityStore for $19.95 (plus tax, postage and shipping, where applicable) and as a searchable, digital application online at nyc.gov/greenbook.