I haven't had a chance to do anything more than glance at it but this might be what you were looking for:
TREATY WITH MEXICO (February 2, 1848)
[By the Louisiana Purchase, Texas had become a part of the United States; but in 1819 it had been ceded to Spain in the negotiations for Florida. Two years later Mexico, including Texas, had become independent, and the United States made two unsuccessful attempts to purchase Texas from Mexico. The settlement of Texas by immigrants from the United States finally led to the secession of Texas and its annexation by the United States, with the result that the Mexican War broke out in May, 1846. It was closed by this treaty, by which the United States gained not only Texas but New Mexico and Upper California.]
TREATY OF PEACE, FRIENDSHIP, LIMITS, AND SETTLEMENT BETWEEN THE UNITED STATES OF AMERICA AND THE UNITED MEXICAN STATES CONCLUDED AT GUADALUPE HIDALGO, FEBRUARY 2, 1848; RATIFICATION ADVISED BY SENATE, WITH AMENDMENTS, MARCH 10, 1848; RATIFIED BY PRESIDENT, MARCH 16, 1848; RATIFICATIONS EXCHANGED AT QUERETARO, MAY 30, 1848; PROCLAIMED, JULY 4, 1848.
cont'd......
http://www.azteca.net/aztec/guadhida.html Thanks, but I'm not the one who needs to see it, they do:
The Brown Berets holding the sign are a paramilitary Aztlan brigade.