Glen Rock enjoyed a period of industrial might from around 1840 to the end of World War II. After the Northern Central Railroad was constructed, Glen Rock grew from a quiet valley settlement with only a wool mill, to a large town featuring a variety of industries. A large machine shop building machining tools, railcars, and drills and an agricultural commissioning company powered Glen Rock’s economy. Various smaller mills and factories rounded out Glen Rock’s industries. The furniture business steadily grew through the turn of the century up until the late 1930’s, offering employment for the residents of Glen Rock. The opening of roads in the area, along with the decline of the railroad, led to Glen Rock’s industries faltering, as nearby Shrewsbury became the principal location for new business developments. Since then, many of the original industries have been closed and the buildings either converted for other uses or demolished. Glen Rock has become primarily an agricultural town, with most farming being done on the hills surrounding the town.