Roads 332 Harbors 174 History 154 Geology 77 Historical geography 60 Fortification 58 Colonial forces 57 Máis ... Colonies 48 Defenses 33 Indians of North America 30 Colonization 27 Land tenure 26 World maps 20 Boundaries 19 Geology, Structural 16 Buildings, structures, etc 14 Economic conditions 14 Discovery and exploration 13 Gravity anomalies 12 Social conditions 12 Cartography 11 Civilization 11 Population 11 Geology, Stratigraphic 10 Coast defenses 9 Land grants 9 Campaigns 8 Magnetic anomalies 8 Politics and government 8 Emigration and immigration 7 menos ...