Finding existing GIS data is a common but often difficult task. Sometimes the data you would like is simply not available, but other times it’s just difficult to find. Here are some strategies for finding data.
Searching for data online is going to require a search engine. Many search engines have advanced options that can help narrow down a search or restrict the results. For example, Google has menus for Settings and Tools, as well as searches targeted to specific results like images.
Keep your search terms broad. Also, try synonyms for terms you are interested in. For example, if you were looking for a shapefile of beaches in California, you might search try separate searches for “beach shapefile” or “coast shapefile”. Also, try synonyms for the data type. “GIS”, “map”, “geospatial”, and “shapefile” might find different but relevant results.
Think about how data might be developed or what kinds of layers would go into your analysis rather than terms that define your final product. For example, you might be interested in identifying areas considered a “food desert” but you might need to look for layers for “census data” and “grocery store locations”.
Search results for geospatial data often fall into one of three categories.
- Good: blog posts explaining where to find data, why there is a lack of data, or what tools could be of use for your field.
- Better: Question board responses on sites like Stack Exchange. These can be a treasure trove of solutions, but also frustrating if your question was posted a while ago and has no answers.
- Best: Sites like repositories with links to download the data you are looking for. Don’t forget to check for metadata so you have some provenance for your data.
Data repositories are places that store data. Many public repositories are themed by subject or by the entity that produces the data. For example, many California counties, the State of California, and the federal government have their own repositories for GIS data, including repositories for specific agencies. Data Basin is an example of subject-specific repository that focuses on data for environmental stewardship.
Researchers in your field may be using datasets that are useful for your research. Read the methods section and citations list to look for sources of datasets and links to how to access the data.
Ask for help
On campus, talk to the Library’s GIS Data Curator or ask on the Geospatial email list. If the data you need is from a particular place, such as a county or conservation organization, you may be able to contact the organization’s GIS, data, or IT staff to ask about the availability of data. Additionally, posting in online forums (such as the aforementioned Stack Exchange), websites, or social media using keywords that describe the data you need (see the discussion above about synonyms) and hashtags to get a broader audience can be fruitful.