How did the alliance system drag countries into the war

The alliance system drag other countries into the war, because of the treaties and peace acts they had made with each other. So if one country was attacked, the countries it had an alliance with. Would have to help fight back with them, and during that time almost every country had an alliance with another. So all it took was for another country with lots of alliances to attack another with just as many. To bring about a huge war, hope this helped.

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.