<u>Broad Context:</u> The "Big Picture" is that the US is trying to annex the Republic of Texas as part of their states, and that Texas already <em>shared many common traits </em>(why? part) with the US, and should join as a state of their choosing, (which means slave or free) (How? part).
<u>Other Context:<em> </em></u><em> </em>The adding of Texas into the US (eventually as a slave state) offsetted the balance between the slaves and free states, and so California (gained after the Mexican-American War) was turned into a free state. Texas was the cause of the Texas Revolution & later on the (already named) Mexican-American War. The adding of Texas, and later the Gadsen Purchase, help create today's US southern border that is shared with Mexico.
hope this helps
Some push factors were the chance to get rich, Dry farming, owning land, escaping the nightmares of the south ( slaves ). There were also longhorns to sell. Some pull factors were relatives and spouses not wanting them to go.
He was so popular because he led the US through the Great Depression and World War II
