Page:Geographic Areas Reference Manual (GARM).pdf/335

 Chapter 15

For many decades, the Bureau of the Census has provided data users with area measurement information. Typically, this has been the calculated area, in square miles or square kilometers, for selected census geographic entities; usually States, counties, and some places and MCDs. It provides this information as a component of the data presentations resulting from each decennial census. Most area measurement information pertains only to land area, but there also have been figures for water and/or total area.

In conjunction with the 1990 census, the Census Bureau, for the first time, published area measurement information for all geographic entities down to the census block level. The geographic scope of this coverage includes the entire territory of the United States, Puerto Rico, and the Outlying Areas—American Samoa, Guam, the Northern Mariana Islands, Palau, and the Virgin Islands of the United States.

A primary original purpose of area measurement information, most of which pertained only to land area, was to provide a basis for calculating population density figures. In response to other needs, the Census Bureau began to provide water and/or total area measurement information. Over time, the Census Bureau has revised its area measurement figures to take into account boundary changes, revisions in shorelines, construction of artificial water bodies, the latest technology for calculating area, and better maps.

Area measurement data first appeared in an 1850 census publication, which reported the land area of the Nation, the States and territories, five major drainage areas, and a few other selected major divisions of the United States. Similar area measurement data appeared in the Notes and References Area Measurement/Water Classification15-1