U.S. Census Bureau - Longitudinal Employer-Household Dynamics

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Base Map Help

In OnTheMap, the Base Map tab allows users to control the look of the map viewer by showing or hiding areas (shaded or outlines), lines, and points as well as the labels that go with them. Each group of areas, lines, or points is known as a "layer." To show or display a layer in the map viewer, simply enable the checkbox in the "Layer" column for the layer you want to show.

An image of a portion of the Base Map tab with the 'Layer' option checked for States and unchecked for 110th U.S. Congressional Districts. The image also contains the text, 'Here, the States layer is being shown in the map viewer but the Congressional District layer is not.

To show or display a layer's labels in the map viewer, just enable the checkbox in the "Label" column for the layer's labels you want to show.

An image of a portion of the Base Map tab with the 'Label' option unchecked for States and checked for both 110th U.S. Congressional Districts and State Legislative Districts (Upper). The image also contains the text, 'Here, the labels for the Congressional District layer and the Upper Chamber State Leg. Districts are being shown in the map viewer, but the labels for the States layer are not.

In the Base Map tab, layers are grouped by common usage. Layer groups include "Regional Layers," "Local Layers," "Transportation Layers," "Workforce Layers," "Education Layers," and "Other Layers." By clicking on the layer group name, you can shrink the group so the layers are hidden. This allows you to display only the groups that contain layers you are using.

An image of a portion of the Base Map tab showing how the layer groups can be collapsed or hidden. The image also contains the text, 'In this example, the Transportation Layer group is minimized by clicking on it. Clicking on it again will cause those transportation layers in the group to reappear in the Base Map tab. This does not affect whether the Layer/Label appears in the map viewer.

Some Layers do not appear at every zoom level. For example, Local Roads do not appear when the map viewer is zoomed to a regional or national scale because there are too many roads and the map would be unreadable. When a layer is unavailable at a certain zoom level, the name of the layer will appear in gray, bolded font.

An image of a portion of the Base Map tab showing that the Census Tracts and Census Block Groups Layers are grayed out. The image also contains the text, 'At the current zoom level, Census Tracts and Block Groups cannot be displayed. Zoom in on the region by one or more zoom levels to see these layers.

Some layers, like Places, Airports, and Greenspaces have special display features built into them.

The "Places (Fill)" layer displays cities/towns/CDPs/etc. in one of six colors. The choice of color for a given town is arbitrary. Also, the labels for the "Places (Outline)" layer change with the zoom scale. At regional and national zoom levels, places display as points and only the largest ones (by population) are shown. At local zoom levels, higher population places are denoted with larger font labels.

Greenspaces includes parks, cemeteries, and golf courses when they have been made available to the Census Bureau (see Geography Sources for more information). These are displayed with two different colors.

Airports are generally shown as points. However, when boundaries of the airports are available (see Geography Sources for more information), these are shown at the closest zoom levels.

An image showing three maps. The first map shows the symbol for an Airport, the second map shows the colors used to symbolize Places, and the third map shows how Greenspaces are symbolized. The image also contains the text, 'Airport Point and Boundary(when available). Different colors for Places(Fill) Layer. Parks, Cemeteries and Golf Courses.

Source: U.S. Census Bureau, Center for Economic Studies | Contact Us | Last Revised: September 13, 2011