Standard time
In 1870 Charles F. Dowd proposed four time zones based on the meridian through Washington, DC for North American railroads. In 1872 he revised his proposal to base it on the Greenwich meridian. Sandford Fleming, a Scottish-born engineer operating in Canada, proposed worldwide Standard Time at a meeting of the Royal Canadian Institute on February 8, 1879. Cleveland Abbe advocated standard time to better coordinate international weather observations and resultant weather forecasts, which had been coordinated using local solar time. In 1879 he recommended four time zones across the contiguous United States, based upon Greenwich Mean Time. The General Time Convention (renamed the American Railway Association in 1891), an organization of US railroads charged with coordinating schedules and operating standards, became increasingly concerned that if the US government adopted a standard time scheme it would be disadvantageous to its member railroads. William F. Allen, the Convention secretary, argued that North American railroads should adopt a five-zone standard, similar to the one in use today, to avoid government action. On October 11, 1883, the heads of the major railroads met in Chicago at the Grand Pacific Hotel and agreed to adopt Allen's proposed system.
Uniform Time Act
The most noteworthy exceptions are the states of Arizona and Hawaii, the commonwealths of the Northern Mariana Islands and Puerto Rico, and the territories of American Samoa, Guam, and U.S. Virgin Islands, none of which observe Daylight Saving Time. The various Native American nations within Arizona have the right to use or not use DST. The Navajo Nation has chosen to use DST throughout its territory, which includes parts of New Mexico and Utah. In contrast, the Hopi Nation, whose territory is surrounded entirely by the Arizona portion of the Navajo Nation, has chosen not to use DST.