Treaty of Guadalupe Hidalgo, printed treaty with handwritten notations, March 10, 1848
After considerable debate, the U.S. Senate approved for ratification the Treaty of Guadalupe Hidalgo on March 10, 1848, by a vote of 38–14. This annotated Senate copy indicates controversial points in Article V, which designated an 1847 map by J. Disturnell as the basis for the U.S.-Mexico boundary. The Senate rejected a clause limiting changes to that boundary.
Records of the U.S. Senate, National Archives and Records Administration
Documenting the Discoveries
The Treaty of Guadalupe Hidalgo that ended the war with Mexico in 1848 added more than 525,000 square miles of western territory to the United States—an area that now encompasses all or parts of eight states. Members of Congress, recognizing the potential of this territory for settlement, fiercely debated whether or not to allow slavery there and which route a transcontinental railroad should follow through it. To inform future legislation, Congress funded a full report on the region as part of the boundary survey.