Answer:
Yes, it was
Explanation:
The entire goal of manifest destiny was so America could expand westwards. As a result, they had two large territorial ambitions. One was to take all or most of Oregon Country, the other was to expand into Mexico. That was the whole point of Manifest Destiny, which was basically American Imperialism as its finest. It was what caused the purchase of Louisiana, and many people didn't gain benefit from this, such as the Native Americans, which is similar to European Colonialism and Imperialism, with the native population often suffering and not getting that much in return.
While the situation in Oregon led to tensions that almost caused a war over a pig, the Mexican American war was a war that mainly started over Texas. Texas had originally been a part of Mexico, but after numerous factors, including widespread immigration to Texas from parts of the US, Texas would declare independence on March 2, 1836, and claimed large amounts of territory that included present day New Mexico, Oklahoma, Kansas, Colorado, and Wyoming. Mexico however claimed most of this territory still, only giving Texas territory in present day Eastern Texas. This dispute would eventually get caught in the hands of America, when America annexed Texas. This caused the Texan-Mexican dispute to become an American-Mexican dispute, and America quickly went to war with it, taking all of the present day American west. This is what caused Mexico to spiral out of control later on.
