Which transportation development has the greatest long-term impact on the american economy
steamboat
canal system
horse-drawn cart
steam locomotive

steam locomotive was the fastest mode of transportation. therefore it also was spread the fastest. In half a century it spread to almost all of US.

Explanation:

steam boats and canal system transportation were slow moving. the idea of a flat rail road was derived by horse drawn carts. All in all, without a doubt, steam locomotive has had the greatest long term impact on American economy ( even if several inventions and improvisations had to be made through ).

what the first or next guy says

you will need these

an outline of all three paragraphsan identification of the historical era that you are writing aboutan explanation of the term mass productiona description of two ways new technology affected industrya conclusion that shows how new technologies allowed industrialization to grow