The following is a list of American companies that produced, or currently produce clocks. Where known, the location of the company and the dates of clock manufacture follow the name.

Samuel Abbott; Montpelier, Vermont (1830–1861)
Ansonia Clock Company; Ansonia, Connecticut and Brooklyn, New York (1851–1929)
Attleboro Clock Company; Attleboro, Massachusetts (1890–1915)
Bailey Banks & Biddle; Philadelphia, Pennsylvania (1832–1846)
Birge, Gilbert & Co; Bristol, Connecticut (1835)
Birge, Mallory & Co; Bristol, Connecticut (1837–1843)
Birge, Peck & Co; Bristol, Connecticut (1830)
Boardman & Dunbar; Bristol, Connecticut (1811)
Boardman & Wells; Bristol, Connecticut (1832–1843)
Brewster & Ingrahams; Bristol, Connecticut (1843–1852)
Bridgeport Clock Company; (? - 1853)
Chauncey Boardman; Bristol, Connecticut (1813–1823)
Chauncey Jerome; Bristol, Connecticut (1816–1853)
Chelsea Clock Company; Boston, Massachusetts (1887–Present)
Heman Clark; Salem Bridge, Connecticut (1738–1838)
David Wood; Newburyport, Massachusetts (1766–1824)
Dyer, Wadsworth & Company; Augusta, Georgia (1838–1843)
E. Howard & Co., Boston, Massachusetts (1842–Present)
E & A Ingrahams; Bristol, Connecticut (1852–1856)
Elias Ingraham; Bristol, Connecticut (1831–1841)
Elias Ingraham & Company; Bristol, Connecticut (1857–1860)
E Ingraham Company; Bristol, Connecticut (1884–1958)
Eli Terry; Northbury, Connecticut (1795–1852)
E N Welch Company; Bristol, Connecticut (1864–1903)
F Kroeber; New York, New York (1870–1887)
F Kroeber Clock Company; New York, New York (1887–1904)
General Electric
General Time; Norcross, Georgia (1930–2001)
Heman Clark; Plymouth Hollow, Connecticut (1783–1813)
Hotchkiss and Benedict; Auburn, New York (ca. 1835)
Howard Miller Clock Company Zeeland, Michigan (1926–Present)
Ingraham Company; Bristol, Connecticut (1958–1967)
Jennings Brothers Manufacturing Corporation Bridgeport, Connecticut (? - ?)
Luman Watson; Cincinnati, Ohio (1809–1834)
Munger and Benedict; Auburn, New York (ca. 1825)
New England Clock Company; New Haven, Connecticut (1959–Present)
New Haven Clock Company; New Haven, Connecticut (1853–1959)
Parker & Whipple; Meriden, Connecticut (1795–1868)
Parker & Whipple Manufacturing Company; Meriden, Connecticut (1868–1893)
Parker Clock Company; Meriden, Connecticut (1893–1934)
Ray and Ingraham; Bristol, Connecticut (1841–1844)
Reeves & Company; (1820 - ?)
Ridgeway Clocks; Ridgeway, Virginia
Riley Whiting; Winchester, Connecticut and Winstead, Connecticut (1808–1835)
Samuel Whiting; Concord, Massachusetts (1808–1817)
Sangamo Electric Company; Springfield, Illinois (1899–1931)
Seth Thomas Clock Company (1807–Present)
Sessions Clock Company; Bristol, Connecticut (1903–1969)
Standard Electric Time Company; Waterbury, Connecticut, Springfield, Connecticut, and Tecumseh, Michigan (1887–Present)
Time Telegraph Company (1883–1887)
United Clock Company; Peru, Illinois (1853–1887)
Waltham Aircraft Clock Corporation; since 1994 in Ozark, Alabama, continuation of Waltham Precision Instruments Company
Waterbury Clock Company; Waterbury, Connecticut (1857–1967)
Western Clock Company or Westclox; (1885–2001)
William L Gilbert; Winsted, Connecticut (1841–1871)
William L Gilbert Clock Company; Winsted, Connecticut (1871–1934)
William L. Gilbert Clock Corporation; Winstead, Connecticut (1934–1964)
Williams, Orton & Preston; Farmington, Connecticut (1830–1840)

Good stuff Patrick,

Thanks.

Thanks for putting it up all in one place Patrick

Like Dave said, good stuff.
Tim