From the 1850s to the 1890s, the main form of urban mass transportation in the united states was the

Militarism helped spark WWI because nations started to think of military power as a competition, and they wanted to have a stronger military than any other state. This led to tensions and threats that helped spark the war.

Explanation:

Before WWI started, nations began to strengthen their countries through their militaries. For example, nations like Germany and England began building up their armies, which created strong tensions between each other.

Other nations began to work on their militaries as well, leading to the war by creating even more tensions and suspicions.