Because it was expensive to import sugar into the Colonies back in the 18th Century, the colonists would tap the maple trees, similar to the process still used today to gather the sap for making maple syrup. They would then haul the sap filled containers to a sugar shack where it was boiled down in large iron kettles to make sugar and syrup.
By the 19th Century, larger pans were created, and a variety of techniques were developed to help improve the process and make it more efficient. At the same time, cane sugar became readily available in the United States, and the producers focused more on maple syrup than maple sugar.
Today, technologies have provided more ways for producers to streamline the process of creating maple syrup, including energy-efficient boilers and vacuum pumps to move the sap from the trees to the sugar shack.
Source: LOC.gov