Subject
Mexico Boundaries
45
United States Boundaries
44
Continental shelf
4
Border security
3
Mexico Boundaries History
3
Southwest, New Description and travel
3
Texas History
3
United States Boundaries History
3
Auditing
2
Border patrols
2
Border security Auditing
2
Border security Law and legislation
2
Fences Design and construction
2
Illegal immigration
2
Immigration enforcement
2
Mexico
2
Mexico Relations
2
National security
2
Natural history
2
Noncitizens
2
Noncitizens Government policy
2
Rules and practice
2
Terrorism Prevention
2
United States Discovery and exploration
2
United States Foreign relations
2
United States Relations
2
Appropriations and expenditures
1
Border crossing
1
Border patrols Finance
1
Borderlands Emigration and immigration
1
Canada Boundaries
1
Chamizal National Memorial (El Paso, Tex.)
1
Coronado National Memorial (Ariz.) History
1
Drug control
1
Drug traffic Prevention
1
El Chamizal (Mexico and Tex.)
1
Fences Design and construction Costs
1
Gadsden Purchase
1
Geology
1
Gila River (N.M. and Ariz.)
1
Governmental investigations
1
Illegal immigration Government policy
1
Immigrant children
1
Industrial policy
1
Industries
1
Information technology
1
International rivers
1
Latin Americans Social conditions
1
Louisiana Purchase
1
Maritime boundaries
1
more ...