USNG is standard that established a nationally consistent grid reference system. It provides a seamless plane coordinate system across jurisdictional boundaries and map scales; it enables precise position referencing with GPS, web map portals, and hardcopy maps. USNG enables a practical system of geoaddresses and a universal map index. This data resides in the GCS 1983 coordinate system and is most suitable for viewing over North America. The data is separated into three groups, Small Scale Grids, 1000m Grids, and 100m Grids. The small scale grid group contains grids shown at smaller scales including the 6 x 8 decimal degree grids, the 100000m grids, and the 10000m grids. The 1000m grid group shows 1,000 meter grid squares. Due to the large volume of 1000m data, the 1000m grids are separate into UTM zones. This speeds up the querying time of the 1000m grids. The 100m grid group contains 100m grids for various metropolitan area in the U.S. and Puerto Rico. These metropolitan areas are further separate into time zones so it's easier to navigate through the Table of Contents to find a metro area.