Mexico - Countries - Office of the Historian

On December 12, 1822, Mexico was officially recognized as an independent nation by the United States. From the article:

"A Guide to the United States’ History of Recognition, Diplomatic, and Consular Relations, by Country, since 1776: Mexico
Summary
Diplomatic relations between the United States and Mexico have been intimate and often contentious. At the outset, the issue of granting recognition to an independent Mexico divided American leaders such as Henry Clay and John Quincy Adams. After finally recognizing Mexico in 1822, the U.S. push for territorial expansion led to a war between the two countries (1846-48). Political instability in Mexico followed and produced strains in U.S.-Mexican relations. Diplomatic relations have not been severed since 1917.

Recognition
United States Recognition of Mexican Independence, 1822.
The United States recognized Mexico on December 12, 1822, when President James Monroe received José Manuel Zozaya as Mexican Minister to the United States. Earlier Mexican attempts to garner U.S. recognition had failed, largely due to the desire of American presidents to remain formally neutral during hostilities between Spanish forces and independence fighters in the American republics. Previously, Mexico was under Spanish sovereignty. This changed when Napoleon Bonaparte led the French invasion of Spain in 1808, which provided Latin Americans an opening to fight for independence from Spanish colonial rule.

Diplomatic Relations
Establishment of Diplomatic Relations, 1822.
Diplomatic relations were established on December 12, 1822, when President James Monroe received José Manuel Zozaya as Mexican Minister to the United States.

Establishment of the American Legation in Mexico City, 1825.
The American Legation in Mexico was established on June 1, 1825, when Joel Robert Poinsett presented his credentials as Envoy Extraordinary and Minister Plenipotentiary to President Guadalupe Victoria.

Diplomatic Relations Severed by Mexico, 1845.
In 1836 settlers in Texas declared themselves independent from Mexico. The United States recognized the Republic of Texas on March 7, 1837. On August 23, 1843, the Mexican foreign minister informed U.S. Envoy Extraordinary and Minister Plenipotentiary to Mexico, Waddy Thompson, that U.S. annexation of Texas would be grounds for war. On March 1, 1845, U.S. President John Tyler signed a congressional joint resolution favoring the annexation of Texas. On March 4, 1845, U.S. President James Knox Polk noted his approval of the “reunion” of the Republic of Texas with the United States in his inaugural address. In response, the Mexican Minister of Foreign Affairs informed U.S. Minister to Mexico, Wilson Shannon, on March 28, 1845, that Mexico was severing diplomatic relations with the United States. In December 1845 Texas was admitted to the union as the twenty-eighth state. In April 1846, Mexican troops attacked what they perceived to be invading U.S. forces that had occupied territory claimed by both Mexico and the United States, and on May 13, the U.S. Congress declared war against Mexico.

Diplomatic Relations Reestablished, 1848.
The Treaty of Guadalupe-Hidalgo, signed in Mexico City on February 2, 1848, and ratified by the Senate on March 10, 1848, ended the war. Diplomatic relations were reestablished on December 4, 1848, when U.S. President James K. Polk accepted Luis de la Rosa’s credentials as Envoy Extraordinary and Minister Plenipotentiary to the United States.

Diplomatic Relations Severed by the United States, 1858.
Citing mistreatment of U.S. citizens and their property by the Mexican Government, Envoy Extraordinary and Minister Plenipotentiary to Mexico John Forsyth “suspended” relations, on June 21, 1858, between the legation and the conservative government of Miguel Miramón y Tarelo, which had displaced the liberal government of Benito Juárez, pending instructions from President Buchanan. Buchanan assented and recalled Forsyth on July 15, 1858.

Diplomatic Relations Reestablished, 1859.
Diplomatic relations were reestablished on April 6, 1859, when Envoy Extraordinary and Minister Plenipotentiary to Mexico, Robert M. McLane, presented his credentials to President Benito Juárez. McLane also recognized Juarez’s government as the sole legitimate government of Mexico (despite its placement outside the national capital, which was occupied by the rival presidential claimant, Miguel Miramón y Tarelo.)

Elevation of American Legation to Embassy Status, 1899.
The Legation in Mexico was raised to Embassy status on January 3, 1899, when Powell Clayton presented his credentials as Ambassador Extraordinary and Plenipotentiary to President Porfirio Díaz.

Diplomatic Relations Severed by Mexico, 1914.
Following the Tampico Incident of April 9, 1914, when Mexican military forces arrested two U.S. naval officers and seven crew members and marched them through the streets, U.S. President Woodrow Wilson ordered the bombardment and occupation of Veracruz by the U.S. Marines. In reaction to the U.S. occupation of Veracruz, Mexican officials severed diplomatic relations with the United States on April 22, when they handed Chargé d’Affaires ad interim O’Shaughnessy his passport and requested his departure from Mexico (they provided him with a special train to Veracruz, still held by U.S. forces).

Diplomatic Relations Reestablished, 1917.
President Huerta resigned on July 15, 1914. The United States recognized the government of General Venustiano Carranza as the de facto government of Mexico on October 19, 1915, in a letter from the Department of State to the Carranza government. On the same day, Secretary of State Robert Lansing invited Carranza to dispatch a diplomatic representative for formal reception in Washington. Diplomatic relations were reestablished on March 3, 1917, when U.S. Ambassador Henry P. Fletcher presented his credentials to President Carranza."