Blacksmithing was a crucial activity in colonial America, and the blacksmith was often considered to be the most important person in a village. Forges and "tin shops" provided everyday items, from household utensils to farming tools and building supplies, nails, hammers, axes and such, along with the all-important horseshoes (think of them as being like tyres for your car. Essential for travel, really).
Blacksmiths were also a vital part of the logistical chain of any army, since their highly specialized skills were required to either produce or repair weapons and military equipment of all kind, in addition to providing assistance in taking care of horses.
Unsurprising, really – if you're working with a lot of metal things that are often broken, it's handy to have someone around who can fix them.