Geology 1,383 Colorado 736 Mines and mineral resources 577 Auditing 432 Evaluation 426 Colorado History 374 Wildlife management 358 Geology, Stratigraphic 330 Water quality 306 Water-supply 302 Groundwater 262 Medicaid 249 Water resources development 234 Appropriations and expenditures 228 Colorado Politics and government 204 Criminal justice, Administration of 198 Water quality management 194 Sales tax 193 Colorado Economic conditions 177 Educational tests and measurements 175 Colorado Description and travel 173 Uranium ores 171 Emergency management 170 Transportation Planning 157 Income tax 155 Education 153 Finance, Public 153 Education Standards 148 Frontier and pioneer life 142 Land use, Rural 137 Public utilities Law and legislation 137 Water Pollution 135 Water rights 133 Taxation 131 Academic achievement 127 Property tax 127 Occupational training 122 Air Pollution 121 Roads Design and construction 121 Outdoor recreation 117 Colorado Antiquities 116 Groundwater Quality 115 Floods 113 Planning 112 Coal mines and mining 111 Labor market 111 Education Finance 110 Land use 110 Flood insurance 109 Roads 109 Oil-shales 105 Demographic surveys 104 History 104 Coal 103 Management 103 Population aging 101 Real property tax 101 Water Law and legislation 100 Universities and colleges 99 Hydrology 98 Colorado Appropriations and expenditures 97 Health insurance 97 Finance 95 Agriculture 92 Biodiversity 90 Environmental impact analysis 90 Public lands 90 Wetlands 88 Roads Design and construction Environmental aspects 87 Noxious weeds Control 86 Ore deposits 86 Constitutional amendments 85 Indians of North America Antiquities 85 Medical policy 85 Tax credits 85 Child welfare 84 Labor supply 84 Health behavior 83 Transportation and state 83 Drinking water 82 Gold mines and mining 82 Workers' compensation 82 Students with disabilities 81 Trails 81 Forest management 80 Parks 79 Cooking 76 Use tax 76 Stream measurements 75 Deer populations Management 74 Irrigation 74 Historic preservation 73 Historic sites 73 Agriculture Economic aspects 72 COVID-19 (Disease) 71 Community colleges 71 Deer hunting 71 Referendum 71 School-to-work transition 71 Groundwater Pollution 70