Territory between Mexico & American disputed
Polk offered to buy territory from MX for a pitiful price
Mex Pres. Santa Anna sent guards to border to protect MX
Polk sent his men too, hoping MX would fire so they could invade and take the territory by force
That's exactly what happened → ensue the Mexican-American War
War supported by those wanting expansion
MX not annexed because of the Catholic population & non-White race
Treaty of Guadelpue Hidalgo: Polk gets CA, NV, NM, AZ, CO, OK, KS, WY