1) The interaction between the settlers in Texas and Mexican government changed over time, as initially the Mexican government allowed Americans to settle in Texas and bring their slaves. However, as time progressed, there became a huge influx of American citizens bringing their slaves to this territory. This huge increase in slave population worried the Mexican government, as they felt they were losing control of this land. This is why the Mexican government began going back on their word and negating contracts they made previously with white American settlers.
2) The idea of manifest destiny represents America's belief that it was our god-given right to control all land in the North American continent from the Atlantic to Pacific Ocean. With this in mind, the government desired to add Texas to our country because this would help make our dream of manifest destiny a reality.
3) Northern states did not want to add Texas because Texas would be a slave state, thus disrupting the balance of free state and slave state representatives in Congress.
4) The Mexican-American War shaped the US positively, as they gained a significant amount of territory which includes modern day Arizona, California, New Mexico, Utah, and Colorado. This negatively effected Mexico, as they lost 1/3 of their territory to the US.
