From Philly Brownstoner and the inimitable Libby Hawes: "As neighborhoods developed, small commercial districts of rowhouses with first floor store fronts were common. The industrial revolution produced cheaper merchandise, causing a decline in goods made by artisan merchants, but increasing the number of retailers selling factory-made goods. Innovations in storefront designs in the 19th century were due largely to advancements in glass manufacture. Cylinders produced glass up to 4 feet by 6 feet, with fewer imperfections, requiring less framing members. Another revolution in the construction of storefronts was the manufacture of cast iron architectural elements as early as the 1840s." Full post here.