• Area (polygon) layers

• Line layers

• Point layers

The reproductive health indicator rates are displayed as thematic maps. Thematic maps use color (or shades of gray) based on a meaningful classification scheme to reveal geographic patterns in the map layers.

The default layers initially displayed are the indicator area layer and a transparent outline layer of the administrative boundaries of the indicator layer. For example, if counties are chosen as the analysis layer, two layers will initially be visible—the indicator layer and the county outline layer. The indicator layer will display the rate in classification themes and will be the default active layer. The outline layer will highlight the county boundaries. When activated, the county outline layer can be used to obtain census information about the county features.

Other outline layers may be available for display depending on the indicator and scale of the map. To display a layer that is not already visible, click on the check box next to the layer title in the map sidebar.

Area (polygon) layers

P/MSA—primary metropolitan statistical areas (PMSA) and metropolitan statistical areas (MSA) are those established by the U.S. Office of Management and Budget (OMB) using 1990 Census population counts and that were effective with the 1994 data files. For New England, the New England County Metropolitan Areas (NECMA) are used.  There are 311 MSAs, PMSAs, and NECMAs. The title of a metropolitan statistical area (MSA) contains the name of its largest central city and up to two additional central city names, provided that the additional places meet specified levels of population, employment, and commuting. Generally, a place with a population of 250,000 or more is in the title, regardless of other criteria.

County—the primary legal divisions of most states are termed ‘‘counties.’’ In Louisiana, these divisions are known as parishes. In Alaska, which has no counties, the statistically equivalent entities are census areas, city and boroughs (as in Juneau City and Borough), a municipality (Anchorage), and organized boroughs. Census areas are delineated cooperatively for data presentation purposes by the state of Alaska and the U.S. Census Bureau. In four states (Maryland, Missouri, Nevada, and Virginia), there are one or more incorporated places that are independent of any county organization and thus constitute primary divisions of their states; these incorporated places are known as ‘‘independent cities’’ and are treated as equivalent to counties for data presentation purposes. (In some data presentations, they may be treated as county subdivisions and places.) The District of Columbia has no primary divisions, and the entire area is considered equivalent to a county for data presentation purposes. In American Samoa, the primary divisions are districts and islands; in the Northern Mariana Islands, municipalities; in the Virgin Islands of the United States, the principal islands of St. Croix, St. John, and St. Thomas. Guam has no primary divisions, and the entire area is considered equivalent to a county for data presentation purposes. Each county and statistically equivalent entity is assigned a three-digit Federal Information Processing Standards code that is unique within state. These codes are assigned in alphabetical order of county or county equivalent within state, except for the independent cities, which are assigned codes higher than and following the listing of counties. There are 3221 counties or county equivalents excluding the District of Columbia, Guam, the Northern Mariana Islands, and American Samoa which do not have counties or county equivalents.

State—states are the primary governmental divisions of the United States. The District of Columbia is treated as a statistical equivalent of a state for data presentation purposes. For Census 2000, the U.S. Census Bureau also treats a number of entities that are not legal divisions of the United States as statistically equivalent to a state—American Samoa, the Commonwealth of the Northern Mariana Islands, Guam, Puerto Rico, and the Virgin Islands of the United States. Each state and the District of Columbia are numbered alphabetically. US territories are added at the end. In addition, several unique codes are used to identify nonresidents of the United States. There are fifty six states, districts, and territories in the United States.

U.S. Census Regions and Divisions—in decennial census data products from the U.S. Census Bureau, geographic entities are presented in an hierarchical arrangement called the ‘‘standard census geographic hierarchy.’’ The hierarchy has ten levels beginning with the entire country and ending with census blocks. In this arrangement, there are two levels—regions and divisions—above the state level in the hierarchy. There are four regions, and nine divisions under the regions. For the purpose of the atlas, a fifth region (US territories), and a 10th and 11th division (Pacific Oceania and Caribbean Oceania) were added.

Health and Human Services (HHS) Regions—the Department of Health and Human Services (HHS) uses ten regional state groupings to define the HHS service areas.

ZIP Code Tabulation AreasTM (ZCTAs)—a new statistical entity developed by the U.S. Census Bureau for tabulating summary statistics from Census 2000. This new entity was developed to overcome the difficulties in precisely defining the land area covered by each ZIP Code®. Defining the extent of an area is necessary in order to accurately tabulate census data for that area. ZCTAs are generalized area representations of U.S. Postal Service (USPS) ZIP Code service areas. For more information about ZCTAs go to Census 2000 ZIP Code® Tabulation Areas (ZCTAsTM).

Note: Polygon layers are often displayed as simple outlines that can be used to overlay the thematic layer. This often helps to define geographic patterns and link them to known service areas in a meaningful way.

Line layers

Highways, roads and streets—Highways, roads and streets are displayed as a thematic layer using a standard hierarchical method of display. The Interstate highways are the top level of the line/road hierarchy that include Interstate highway, U.S. highway, state highway, county highway, and town and township road at the bottom of the list.

Note: The line layers available in the Interactive Atlas do not automatically become visible—even when the visibility box is checked—until the map is sufficiently zoomed in to a scale that can display them in a meaningful way. 

Point layers

Family Planning (FP) agencies—Office of Population Affairs (OPA) Title X funded (Family Planning) grantees, delegates and clinics. These agencies have been geocoded from the OPA Family Planning (FP) national dataset using the most current Geography Data Technology (GDT) address matching database.

Note 1: The point layers available in the Interactive Atlas do not automatically become visible—even when the visibility box is checked—until the map scale is sufficiently zoomed in to a scale that can display them in a meaningful way. 

Note 2: Address matching is not a perfect science therefore some of the points will not represent the actual physical location of the agency, however all points have been placed in the appropriate county for each agency.

Page last reviewed: 7/28/08
Page last modified: 1/29/07
Content source: Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion