I stumbled across some information regarding the history of Cape Cod that mentioned salt making and the amount of salt produced annually. In the report dated 1839 is stated "About two millions of dollars are invested in the manufacture of salt. There were manufactured in this county in the year ending April 1,1837, 669,064 bushels of salt, valued at $219,870. " (John Hayward's 1839 New England Gazetteer). This made me wonder just how they made salt from salt water, oh I know it means evaporating the water out of the ocean but I wondered just how they went about doing it.
So I found this brief description from the "Library of Cape Cod History and genealogy, Issue 78 page 30 ©1912 that I found very informative. I hope you do as well.
Prior to 1860 and particularly early in the 19th century, shipbuilding was carried on to some extent, small vessels being turned out of the works. In 1845 six vessels were built and in 1855 fifteen. The business of making salt by the evaporation of sea water was early established here Extensive shallow vats were built along the shores of the bays, equipped with movable roofs so that they could be covered on the approach of rain. The water was pumped into them by windmills. The last works that were operated were those of Jesse Nickerson on the neck where the hotel Chatham stood. These were closed about 1886. In 1802 there were six salt works in the town; in 1837, 80, producing annually 27,400 bushels, worth $8,220; in 1845, 54, producing 18,000 bushels; and in 1855, 14, producing 3,300 bushels. The industry ceased to pay and began to decline when duties on salt were lowered, when the State bounty was removed, when salt springs in New York and elsewhere in the country came to be developed, and when the price of pine lumber necessary in the construction of the works rose to a high level. General manufacturing was never carried on here to any extent.