Who provoked whom in the crisis between mexico and the united states

 We have the foreign polity that places and keeps leaders in power that opress their inhabitants. It is in our history and we continue with it today. There were uprisings in Mexico that United States soldiers thwarted. The Mexicans would have naturally revolted but we stopped them. Then bad things happened and we made up the crisis (I'm pretty sure we went after someone and killed him) to get the revolutionaries on our side again and created a war. We are the culprits and we provoked ourselves in the crisis. I have a good friend who knows way more about history than I do and if you like email me and I'll find out more details. 

Advances in learning and technology made long ocean voyages possible

The changes to agriculture in the united states since 1900 is that increased mechanization has increased food production, thereby increasing the need for labor. there has been an increased need for higher speeds of food production due the fact that the population in the united states continues to rise.