Many small firms emerged in the wake of Eli Terry's success, copying his process and product. By the 1830s the market was flooded with Connecticut-made wooden movement shelf clocks which were being peddled in cities and frontier towns alike. While keen competition drove down profits and quality, it also lowered prices, meaning more and more people could afford a clock.
The depression of 1837 crippled American industry, closing about 90 percent of the Northeast's factories. The clock industry was not immune, and weaker firms folded. The industry received a much-needed boost with the introduction in 1839 of an inexpensive brass movement shelf clock by Chauncey Jerome (1793-1868) of Bristol, Connecticut. Joseph Ives (1782-1862), also of Bristol, preceded Jerome by twenty years in the manufacture of brass-movement shelf clocks, but Ives' clocks cost three to four times the price of a wood clock. Jerome's new clocks, on the other hand, sold for $6 cash, only a few dollars more than a wood-movement clock. It was more rugged, cheap to make, and easy to repair. Unlike wood-movement clocks, which would swell and warp at sea, the brass-movement shelf clock shipped well and thus was a viable candidate for foreign markets.
Though expensive flat leaf spring-powered clocks were made by Joseph Ives as early as 1825, it was not until the development of less expensive coiled springs nearly two decades later that spring clocks were widely adopted. Spring-driven clocks could be made dramatically smaller since long cases for weight travel were not necessary. Since materials—not labor—comprised the bulk of a clock's cost, smaller clocks meant lower prices and larger profits. Between 1840 and 1850, the average clock shrunk in size by at least 30 percent.
By 1850, over half a million brass shelf clocks were being manufactured by fifteen clockmaking firms in Connecticut. By that time one in three central New England households had a clock; most of these were Connecticut made.
At the end of the Civil War, dozens of firms which had been doing business thirty years earlier collapsed or consolidated, and seven major clock manufactures emerged. These seven firms would dominate the industry during the century that followed. They were the Ansonia Clock Company (1850-1929), the New haven Clock Company (1853-1959), the Seth Thomas Clock Company (1853-present), the Waterbury Clock Company (1857-1967), the William L. Gilbert Clock Company (1866-1964), and the E.N. Welch manufacturing Company (1864-1903), which was succeeded by the Sessions Clock Company (1903-1968).
Chris Bailey writes in the Two Hundred years of American Clocks and Watches that the years 1880 to 1920 were a "Golden Age" for these seven giants during which they enjoyed "good profits, good sales on domestic and foreign markets, constant improvements and refinements in manufacturing techniques, and greater volume production." However, the Great Depression, World War II, inflation, rising labor costs, and competition from German and Japanese manufactures would lead to their eventual demise and the general cessation of clockmaking in America.
During the 19th century, American clockmakers changed the face of clockmaking forever. Craft had become industry as factories replaced workshops. Eli Terry's production of 4,000 clock movements between 1806 and 1809 had astonished his peers. A century later, Connecticut factories were turning out about 8,000 wood-cased clocks daily, and nearly twice as many nickel-drum alarm clocks, many of the latter selling for less than one dollar. American clockmakers had lived up to their country's democratic ideals: they had made timekeeping, once the province of the elite, the property of the masses.