Аж үйлдвэржилтийн хувьсгал. Аж үйлдвэрийн 1р хувьсгал …
1825 — The Erie Canal is completed opening a water route from the Great Lakes to New York City and the Atlantic Ocean. 1831 — The mechanical reaper is invented by Cyrus McCormick. 1837 — A blacksmith named John invents the steel plow. 1844 — The telegraph is invented by Samuel Morse.