After Marblehead, we went to the Cuyahoga Valley National Park. A good part of the Park is comprised of the remnants of the Ohio and Erie Canals. It was a pretty interesting place.
Construction of the canal began in 1825 and by 1832, you could go all the way from Clevland to Cincinatti in a much shorter period of time (part of that was by the Ohio River). It was four feet deep and was dug by hand by Irish and German immigrants. Freight traveled on it until 1861 (and maybe a little bit beyond) when the railroads started to take over. It was continued until 1913 for use a water supply for the industries and farms along the way.
When the canal was built, Ohio was wild country but the canal allowed the state to prosper. It became one of the richest and most populous states in the country.