United States 110 Geology 50 Mines and mineral resources 48 Housing 35 Computer files 29 United States Population 27 Older people 26 United States Economic conditions 20 Geographic information systems 19 Ore deposits 17 Digital mapping 16 Educational surveys 16 Groundwater 14 Health behavior 14 Information services 14 Water quality 14 Industrial statistics 13 Public health 13 Agriculture 12 Demographic surveys 12 Geochemistry 12 Income 12 Land grants 12 Database management 11 Geomagnetism 11 Health surveys 11 Land titles Registration and transfer 11 Stream measurements 11 Education 10 Election districts 10 Geodatabases 10 Government publications 10 Hydrology 10 Petroleum industry and trade 10 Transportation 10 Census districts 9 Foreign worker certification 9 Gas industry 9 Health risk assessment 9 Hydrogeology 9 Seismic prospecting 9 Zip codes 9 Air Pollution 8 Geology, Stratigraphic 8 National income Accounting 8 Natural gas Prospecting 8 Occupations 8 Petroleum Prospecting 8 Streets 8 Water-supply 8 Childbirth 7 Earth sciences 7 Gross national product 7 Land use 7 Public schools 7 Water Pollution 7 Auditing 6 Business 6 Criminal justice, Administration of 6 Databases 6 Education, Higher 6 Emergency management 6 Exports 6 Geology, Structural 6 High school graduates 6 Information storage and retrieval systems 6 Information storage and retrieval systems Geology 6 Law enforcement 6 Pollution 6 Science 6 United States Climate 6 Water quality management 6 Agriculture States 5 Ambulatory medical care Utilization 5 Aquifers 5 Climatic changes 5 College attendance Longitudinal studies 5 Earthquakes 5 Education, Secondary 5 Geological mapping 5 Geophysics 5 Government information 5 Imports 5 Infants Mortality 5 Information resources management 5 Information storage and retrieval systems Education 5 Information storage and retrieval systems Government publications 5 Juvenile delinquents 5 Management information systems 5 National parks and reserves 5 Natural gas reserves 5 Paleontology 5 Petroleum reserves 5 Postsecondary education Longitudinal studies 5 Registers of births, etc 5 Solar radiation 5 South Carolina Population 5 Students Longitudinal studies 5 Atmospheric temperature 4 Cartography 4