In 1786 why did america need a new stronger national government?

The Annapolis Convention

To address the problems with the Articles of Confederation, delegates from five states met at the Annapolis Convention in Maryland in 1786. However, they could not agree on how these issues should be resolved. Finally, a new convention was proposed for the following year with the express purpose of revising the Articles of Confederation.

To be straight up and honest with you, it was because the Articles of Confederation sucked, and couldn't maintain anything in the government, hence the creation of the Constitution a way better approach to government.

that would be the steamboat because none of the other things are forms of transportation

this is a good question! i'll do some research and come back when i have the answer!