Social Explorer is the choice if you are looking for historical census data. In Social Explorer you will have access to the U.S. Decennial Census back to 1790 as well as the data from the American Community Survey from 2005 to 2013. This is also the source for the Religious Congregations and Membership Study (RCMS) for 1980, 1990 and 2000, the Infogroup Religion 2009 and 2010 and the 2002 Carbon Dioxide Emissions data.
Social Explorer is a web-based mapping and data visualization tool. Access is provided by the Yale University Library to everyone at Yale. You can access Social Explorer at www.socialexplorer.com. If you are not on campus, you will need to use the VPN to get access.
You do not have to create an account to access the data and visualization tools in Social Explorer. You can create a free account if you wish to create and save projects. Do not use your NetID and password as your log in. You can choose to create a public profile if you wish.
You can change the data that is displayed on the map by clicking on the Change Data button in the top left corner of your screen. There are two options for browsing the data - by Category of by Survey.
Browsing by Category requires that you choose a survey year first. Different data are available depending on the survey year that you choose. The available survey data go all the way back to 1790.
Browsing by Survey allows you to choose your data source. You can choose from the available years of the American Community Survey (ACS), the decennial Census, the Religious Congregations & Membership Study (RCMS), the Religion studies by InfoGroup, and the 2002 Vulcan Project Carbon Emissions Data. You then choose the table and variable you are interested in.
By default, the map will show the data geography that has been set as appropriate for the scale of the map (probably at the State level). You can see the map scale in the bottom left corner of the map. Use the -/+ buttons to zoom out and in, respectively. You can also zoom using the scroll wheel on your mouse. From Zoom 1-5 you will see state level data, Zoom 6-9 you will see County data, and above Zoom 10 you will see Census Tract level data (where those levels are available).
You can manually choose the data geography in the Show data by: pull-down menu. Turn the Automatic slider to Off and then click on the appropriate radio button. If the data disappear from the map you have chosen a geography that does not exist for that data set.
Social Explorer offers you three different visualization types; shaded areas (choropleth maps), bubbles (proportional symbols) and dot density. According to Chapter 3 in The Nature of Geographic Information (a great resource if you are just starting out with GIS), if the variable that you are mapping is straight counts of indviduals you should use Bobbles or Dot Density. If you are mapping rates or densities, use shaded areas.
Shaded area maps display data as a series of colors that fill in geographic areas. You can change When you are looking at a series of values from lowest to highest, it is best to use a color scale that goes from a light shade to a dark shade of one color. There are many options for color scales in Social Explorer or you can create your own. If the order of the color scale does not meet your needs you can Flip colors - this will change the color gradient so that what was previously the darkest colour is now the lightest.
In the Bubble visualization type, the data will be represented by a series of circles that are centered in the mid-point of the geographic area they are representing. The scale of the bubbles is shown on the right side of the options menu bar. You can click on it to change the size or color of the bubbles. The +% Add perentages button allows you color-code the bubbles based on the percentage of the total value of the variable that they represent.
In the dot density visualizations, one dot is given a value and then a random scattering of dots is used to represent the variable value for that level of geography. For example, if a dot represented 10,000 households and the value for a county was 11,500 households that county would have one dot. Note that the value represented by one dot will decrease as you zoom in and the number of dots in a geography will increase.
You can change the map layout using the button in the center bottom of the map. There are three layout options.
Shows a single map window with one variable.
Shows two completely independent map windows side by side. There is no connection between these maps - you can change the variables, the zoom, the area that you are looking at, and the visualization type as you please.
The swipe option allows you to look at two different variables in the same geographic context. The location stays the same, but you are allowed to adjust all of the other options on either side of a vertical slider. Move the slider from side to side to change what is represented on the map from one set of variables to another. You can see an example here.