The major reasons why WW1 began had been due to territorial expansion overseas, hatred of other countries, alliances between countries, growing powers in Europe, Different political ideologies, naval expansion, competition for natural resources, and political assassination.
Pre-World War One the German-Empire was a newly made major power that threatened other existing countries such as France and Britain. The German Empire was an authoritarian-monarchy with Kaiser Wilhelm II at the top. Germany and Britain had very big navies which made the British a little insecure. France still hated the Germans due to the Franco-Prussian War in which France lost the territory of Alsace-Lorriane. France was also a republic at the time which usually despise monarchies but created an alliance with Russia and Britain called the Triple Entente. In response, Germany created the Triple Alliance with the Austrian-Hungarian Empire and the Kingdom of Italy that would later join the Entente during WW1. The overseas territory was also in competition as Germany and Britain wanted natural resources from these colonies. When the assassination of Archduke Francis-Ferdinand happens, it sparked a chain reaction of these growing tensions to suddenly bring these nations/ empires into World War One.
The Chinese and the Mexican-Americans were the bulk of workers who built the American transcontinental rairoad in the 19th century. The Chinese arrived in large numbers in the second half of the century escaping poverty and turmoil in China, and there were large Mexican populations living in the USA. Only agricultural work offered more employment to Mexicans than the railroad works.
