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The Santa Fe Trail
First traveled by American in 1821, the Santa Fe Trail became a frequently used transportation route for traders seeking to do business with the country of Mexico, which controlled the New Mexico region. The trail started in Independence, Missouri, and as westward traffic increased, more Americans began to settle in New Mexico. -
Manifest Destiny defined
In a piece written in the New York Morning News, John L. O'Sullivan, in reference to American expansion, declares, "And that claim is by right of our manifest destiny to overspread and to possess the whole of the continent which Providence has given us for the development of the great experiment of liberty and federated self-government." entrusted to us." -
Texas Border Dispute
Mexico claimed Texas as its own. President James K. Polk believed the border between Texas and Mexico lay along the Rio Grande River. Mexico argued that the border lay along the Nueces River, 150 miles north of the Rio Grande River. Polk sends John Slidell to negotiate with Mexico not only over the border dispute regarding Texas, but also for the acquisition of California and New Mexico. Mexico refuses to meet with Slidell. -
John L. O'Sullivan and Annexation of Texas
O'Sullivan, a newspaper columnist, argues for westward expansion and for Texas joining the United States in the July-August 1845 edition of The United States Magazine and Democratic Review in an article entitled, "Annexation." -
War breaks out between Mexico and the United States
President Polk sends U.S. troops into the disputed borderland with Texas, where they are attacked on April April 25. On May 11, President Polk states to Congress that Mexico had "invaded our territory and shed American blood upon the American soil." Congress declares war on Mexico. Polk's goal is to acquire New Mexico, California, and to extend the border of Texas with Mexico to the Rio Grande River. -
Bear Flag Republic established
A group of American settlers captures the town of Sonoma north of San Francisco. They declare it the independent Republic of California. They called the new country the Bear Flag Republic. -
John Fremont takes control of the Bear Flag Republic
Army major John C. Fremont arrives in Sonoma, California, and declares he is going to conquer the rest of the Californian territory by force. He takes control of the Bear Flag Republic from its orginal founders. The U.S. Navy under the command of Commodore John Sloat captures San Francisco and Monterrey. Fremont sails south with Sloat's fleet in order to capture San Diego. -
New Mexico comes under U.S. control
American troops under General Stephen Watts Kearney follow the Santa Fe Trail and are able to march into the capital of the territory and take control of it without firing a shot. -
U.S. control over California is established
Troops under the command of General Stephen Watts Kearny puts down a revolt in San Diego. California is now fully under the control of the United States. -
Zachary Taylor secures Texas border and northern Mexico
Under the leadership of General Zachary Taylor, U.S. troops gain control of the 150 miles of land between the Nueces and Rio Grande Rivers in order to settle the border dispute with Mexico. In addition, Taylor's troops quickly moved south into Mexico, winning control over the country as far south as Monterrey and Buena Vista. -
Mexico surrenders
U.S. troops under General Winfield Scott capture Mexico City. Mexico surrenders and would eventually be forced to give up over half its territory. -
Treaty of Guadalupe Hidalgo
U.S. and Mexico sign treaty ending the Mexican-American War. Mexico gives up control over Texas and agrees to the Rio Grande River as the Texas-Mexico border. In what is referred to as the Mexican Cession, Mexico gives up control over New Mexico and California in exchange for $15 million. -
Gadsden Purchase
For the price of $10 million, the U.S. acquires parts of the southern New Mexico territory. Part of the land acquired would become part of the state of Arizona. With the Gadsden Purchase, the U.S. mainland reached its present day size.
