Last week's House hearing on the state of Federal geospatial data management encouraged me to search out good places for both free and inexpensive GIS data. Basically, I wanted to create a brief overview about good places to find GIS data. I will mostly likely post several blog postings on this issue as I discover new places to find data.
With the growing number of users learning to use GIS in both their professional and private lives, the need for an organized data management system is apparent. Unfortunately, there is currently not a one-stop-shop for GIS data, and as more applications of GIS evolve, the problem of creating a centralized data management system becomes more difficult. The fact that there is not a centralized source of data speaks to both the complex professional application of GIS, and the lack of interest and understanding of spatial sciences by the broader public and politicians. There are so many applications of GIS, it is difficult to create an accurate overview about finding data that includes sources that would benefit all academic and professional interests. One problem that faces many GIS users is that some data is either very expensive, or classified to be used only by professionals with specific credentials. Thus, finding data is not always an easy process, especially for new GIS users. For example, crime data for individual cities is generally not published for the public to download and analyze. Typically, police officials must be contacted in order for data to be shared, which can be a difficult process for those unfamiliar with local police officials. Therefore, this overview will not cover the specific ways to obtain more advanced data sets. This first overview covers where GIS users can go to find data that are mainly published by governmental agencies. Most of the websites listed below have data related to demographics, geography, environment, politics, and culture.
The United States Government's Geosptatial Data Portal is the closest thing to a one-stop-shop for geospatial data. The website provides numerous data sets for a variety of research interests. Most of the data sets are related to health, environment, geography, and demographics. Much of the data provided on this website are contained on other government websites, which was an issue mentioned in the House of Representatives hearing on the current state of government geospatial data. They mentioned that much of the government's geospatial data is redundant, which appears to be the case when the data contained on this website is compared to other websites like the U.S. Census Bureau. However, it appears that some progress has been made in attempting to get a collection of geospatial data together, but as the House hearing mentioned, there is still a great need for more funding and attention to be paid to this important issue. Despite the need for even more centralization of geospatial data, this website provides a great place to find data for analysis in GIS.
The United States Census Bureau offers many different kinds of spatial data. One of the greatest aspects of the U.S. Census is that it is geographic in nature. This means that before the census is conducted there are predefined areas, known as block groups and tracts, that data will be aggregated to. This allows GIS users to quickly download any of the census data into tabular form, which can then be easily imported into Cartographica. Additionally, users can download numerous base-maps that include county boundaries, streets, block groups, census tracts, and other important geographic data . The U.S. Census Bureau is a great place to find data that contains demographics about whole cities or the individual areas of cities that can be used as proxies for neighborhoods. The number of academic studies that have employed U.S. Census data are countless, which speaks not only to the quality of the data, but also to the perception of the data among the academic community.
The United States Geological Survey offers several types of data that are used for analyzing geological phenomenon. The USGS website offers Digital Elevation Modules (DEM), Digital Raster Graphics, Digital Line Graphics, and Digital Orthoqudrangels that can be downloaded and used like a map. There are also National Hydrology data sets and National Elevation data sets that provide detailed depictions of elevation and water features throughout the country. The website also has a National data set for land use and land cover, which describe the types of natural or man-made elements that are covering the land.
The USDA provides numerous data sets about issues related to agricultural production in the United States. Some of the data provided includes ERS regions, agricultural production zones, fields that describe counties metro or rural status, cropland production, and many more useful data sets. Most of the data available on the website is able to be downloaded as a shapefile directly from the website.
These four website combined provide a lot of GIS data that is downloadable for free, but can be used in fairly complex studies. Much of the data will require some manipulation in order to fit specific research topics, but once this is done users will be able to produce solid research based on data that is among the best available.