Which treaty ended the United States' war with Mexico in 18487

Ahistorian studying urban history in chicago in in the early 1900's. she is studying the population changes and the activities that people did in their everyday lives. based on the description which school of thought does the historian likely belong to

The system of checks and balances ensures that

The quote below is an excerpt from the charter of the united nations: "the purposes of the united nations are: to maintain international peace and security, and to that end: to take effective collective measures for the prevention and removal of threats to the peace, and for the suppression of acts of aggression or other breaches of the peace, and to bring about by peaceful means, and in conformity with the principles of justice and international law, adjustment or settlement of international disputes or situations which might lead to a breach of the peace . " source:this section implies that the united nations is prepared to do what to keep world peace?