A curated collection of GIS datasets, maps, apps, and data layers. Living Atlas is a great first place to look for data because you can be sure the datasets are of high quality. However, the collection is relatively small (less than 20,000 datasets), so you may need to try other collections, too.

A large repository of data uploaded by ArcGIS community users. Be sure to pay attention to authorship and read metadata because quality varies!

A state-level repository of GIS formatted data for Minnesota (over 1000 datasets)

Wei-Hsin Fu in the Carleton Spatial Analysis Lab maintains this comprehensive list of portals to GIS data maintained by federal and state angencies.

An evolution of the Geospatial One-Stop E-Gov initiative, this web site allows one to search or browse data categories of geospatial information. The GeoData Map Viewer allows you to view multiple Internet map services (like the National Map) using just your browser. Map servers viewable include the USGS, FEMA Hazard Maps, NASA Globe program, NOAA, and the BLM. State and regional servers are being added, including the Minnesota Metro GIS Data Finder.

The U.S. government's open data portal. Limit by geospatial data for GIS-ready datasets.

An example of a university geospatial data repository. Find similar repositories at other large universities.

An example of a research collaboration between NASA and Columbia University to provide a repository of data, including geospatial data.

An example of a collection of geospatial datasets collected for research purposes, buried on a larger website.