Thomas Edison was born in
Milan, Ohio, and grew up in
Port Huron, Michigan. He was the seventh and last child of Samuel Ogden Edison Jr. (1804–1896, born in
Marshalltown, Nova Scotia) and Nancy Matthews Elliott (1810–1871, born in
Chenango County, New York).
 His father, the son of a
Loyalist refugee, had moved as a boy with the family from Nova Scotia, settling in
southwestern Ontario (then called
Upper Canada), in a village known as Shewsbury, later
Vienna, by 1811. Samuel Jr. eventually fled Ontario, because he took part in the unsuccessful
Mackenzie Rebellion of 1837.
 His father, Samuel Sr., had earlier fought in the
War of 1812 as captain of the First Middlesex Regiment. By contrast, Samuel Jr.'s struggle found him on the losing side, and he crossed into the United States at
Sarnia-Port Huron. Once across the border, he found his way to Milan, Ohio. His patrilineal family line was Dutch by way of New Jersey; the surname had originally been "Edeson."
Edison only attended school for a few months and was instead taught by his mother.
 Much of his education came from reading R.G. Parker's
School of Natural Philosophy and
The Cooper Union for the Advancement of Science and Art.
Edison developed hearing problems at an early age. The cause of his deafness has been attributed to a bout of
scarlet fever during childhood and recurring untreated middle-ear infections. Around the middle of his career, Edison attributed the hearing impairment to being struck on the ears by a train conductor when his chemical laboratory in a boxcar caught fire and he was thrown off the train in
Smiths Creek, Michigan, along with his apparatus and chemicals. In his later years, he modified the story to say the injury occurred when the conductor, in helping him onto a moving train, lifted him by the ears.
Edison's family moved to
Port Huron, Michigan, after the railroad bypassed Milan in 1854 and business declined.
 Edison sold candy and newspapers on trains running from Port Huron to Detroit, and sold vegetables. He briefly worked as a telegraph operator in 1863 for the
Grand Trunk Railway at the railway station in
Stratford, Ontario, at age 16. He was held responsible for a near collision. He also studied qualitative analysis and conducted chemical experiments on the train until he left the job.
Edison obtained the exclusive right to sell newspapers on the road, and, with the aid of four assistants, he set in type and printed the Grand Trunk Herald, which he sold with his other papers.
 This began Edison's long streak of entrepreneurial ventures, as he discovered his talents as a businessman. These talents eventually led him to found 14 companies, including
General Electric, still one of the largest
publicly traded companies in the world.