Mexican culture is a fabulous thing. Sadly, a country that kills its own people isn't a fabulous thing. The USA has the strongest military in the world, all you would need to do is go and defeat he military and put the drug dudes in prison and -poof- yours for the Taking! The place is so tatally beautiful, with fascinating desert in the north and rainforest in the south. Who doesnt want a tropical place to hang?
Look Mexico is a corrupt nation that is falling apart. Plus, up here in America we have a serious illegal immigration problem. Why take the time to push them back into their own country, when we could just defeat their corrupt government, annex Mexico, make it part of America, and help the citizens. We'll have extra resources and more land, and all the citizens can become Americans.
They are going to jump either way so we might as well let them it is it will also solve drug problems we can search them too so it will be even then we wont have the problems that knocks out two birds with one stone. So that's is why
We annexed what is now Texas from Mexico in the mid 1800's. Though our US history books paint the Mexican American war in a different light, it was for the most part a war based on fabrication and a policy of Eminent domain to further US interest. The US offered to buy the territory from Mexico but, they decline; we just took it.