GIS Links -- Data and Information

ESRI
    ArcData -- various links to GIS data
    ArcScripts
    ESRI homepage

Illinois
    Illinois Natural Resources Geospatial Data Clearinghouse

Iowa
    Iowa Geographic Map Server
    Iowa Geospatial Data Clearinghouse

Hawaii
    Hawaii Data Clearinghouse
    Hawaii Statewide GIS Program

Kansas
    Kansas Data Access & Support Center

Michigan
   
Michigan Geographic Data Library

Minnesota
    Minnesota DNR Data Deli

Missouri
    Missouri Spatial Data Information Service

National Atlas (to be removed from service 9/30/2014)
  
National Atlas Home Page
    National Atlas Data Download

National Park Service
   
GIS Data and Information Data Clearinghouse

Nebraska
    Nebraska GIS Data (U of Nebr-Lincoln School of Natural Resources
   Neb Shared GIS Services

North Dakota
    North Dakota Geographic Information Systems

Topical Sites
    GIS 4 Geomorphology

United Nations Environment Programme
   
Environmental Data Explorer

U. S. Bureau of Land Management
    California Geospatial Data
    Nevada Geospatial Data

U. S. Environmental Protection Agency
    National Geospatial Program

U. S. Department of Agriculture / NRCS
   
Geospatial Data Gateway

U. S. Geological Survey
    EarthExplorer
    Eros Home Page
    Global Visualization Viewer (GloVis)
    The National Map

    National Map Viewer
    The USGS Store
    Water-related datasets

U.S. Fish and Wildlife Service
   
Geospatial Services

Utah
    Utah Automated Geographic Reference Center

Virginia
    University of Virginia Library -- Digital Maps and Geospatial Data  

Wisconsin
    Wisconsin Dept of Natural Resources Geographic Information Systems
    Wisconsin DNR -- WebView
   
Wisconsin State Cartographer's Office

    WisconsinView

Wyoming
    Wyoming Spatial Data Clearinghouse -- AI export files, MI files, DRGs