Harold Adams Innis (; November 5, 1894 - November 8, 1952) was a Canadian professor of political economy at the University of Toronto and the author of seminal works on media, communication theory, and Canadian economic history. Despite his dense and difficult prose, Innis was one of Canada's most original thinkers. He helped develop the staples thesis, which holds that Canada's culture, political history, and economy have been decisively influenced by the exploitation and export of a series of "staples" such as fur, fishing, lumber, wheat, mined metals, and coal.

Harold Adams Innis was born in 1894 on a small livestock and dairy farm near the community of Otterville in southwestern Ontario's Oxford County. As a boy he loved the rhythms and routines of farm life and he never forgot his rural origins. His mother, Mary Adams Innis, had named him 'Herald', hoping he would become a minister in the strict evangelical Baptist faith that she and her husband William shared. At the time, the Baptist Church was an important part of life in rural areas. It gave isolated families a sense of community and embodied the values of individualism and independence. Its far-flung congregations were not ruled by a centralized, bureaucratic authority. Innis became an agnostic in later life, but never lost his interest in religion. According to his friend and biographer Donald Creighton, Innis's character was moulded by the Church: The strict sense of values and the feeling of devotion to a cause, which became so characteristic of him in later life, were derived, in part at least, from the instruction imparted so zealously and unquestioningly inside the severely unadorned walls of the Baptist Church at Otterville. Innis attended the one-room schoolhouse in Otterville and the community's high school. He travelled 20 miles (32 km) by train to Woodstock, Ontario, to complete his secondary education at a Baptist-run college. He intended to become a public-school teacher and passed the entrance examinations for teacher training, but decided to take a year off to earn the money he would need to support himself at an Ontario teachers' college. At age 18, therefore, he returned to the one-room schoolhouse at Otterville to teach for one term until the local school board could recruit a fully qualified teacher. The experience made him realize that the life of a teacher in a small, rural school was not for him. Harold Innis wrote his PhD thesis on the history of the Canadian Pacific Railway (CPR). The completion of Canada's first transcontinental railway in 1885 had been a defining moment in Canadian history. Innis's thesis, eventually published as a book in 1923, can be seen as an early attempt to document the railway's significance from an economic historian's point of view. It uses voluminous statistics to underpin its arguments. Innis maintains that the difficult and expensive construction project was sustained by fears of American annexation of the Canadian West. Innis argues that "the history of the Canadian Pacific Railroad is primarily the history of the spread of Western civilization over the northern half of the North American continent". As Robert Babe notes, the railway brought industrialization, transporting coal and building supplies to manufacturing sites. It was also a kind of communications medium that contributed to the spread of European civilization. Babe writes that, for Innis, the CPR's equipment "comprised a massive, energy-consuming, fast-moving, powerful, capital-intensive 'sign' dropped into the very midst of indigenous peoples, whose entire way of life was disrupted, and eventually shattered as a result. Communications scholar Arthur Kroker argues that Innis's study of the Canadian Pacific Railway was only the first in which he attempted to demonstrate that "technology is not something external to Canadian being; but on the contrary, is the necessary condition and lasting consequence of Canadian existence". It also reflected Innis's lifelong interest in the exercise of economic and political power. His CPR history ends, for example, with a recounting of Western grievances against economic policies, such as high freight rates and the steep import tariffs designed to protect fledgling Canadian manufacturers. Westerners complained that this National Policy funnelled money from Prairie farmers into the pockets of the Eastern business establishment. "Western Canada", Innis wrote, "has paid for the development of Canadian nationality, and it would appear that it must continue to pay. The acquisitiveness of Eastern Canada shows little sign of abatement." In 1920, Innis joined the department of political economy at the University of Toronto. He was assigned to teach courses in commerce, economic history and economic theory. He decided to focus his scholarly research on Canadian economic history, a hugely neglected subject, and he settled on the fur trade as his first area of study. Furs had brought French and English traders to Canada, motivating them to travel west along the continent's interlocking lake and river systems to the Pacific coast. Innis realized that he would not only need to search out archival documents to understand the history of the fur trade, but would also have to travel the country himself gathering masses of firsthand information and accumulating what he called "dirt" experience. Thus, Innis travelled extensively beginning in the summer of 1924 when he and a friend paddled an 18-foot (5.5 m) canvas-covered canoe hundreds of miles down the Peace River to Lake Athabasca; then down the Slave River to Great Slave Lake. They completed their journey down the Mackenzie, Canada's longest river, to the Arctic Ocean on a small Hudson's Bay Company tug. During his travels, Innis supplemented his fur research by gathering information on other staple products such as lumber, pulp and paper, minerals, grain and fish. He travelled so extensively that by the early 1940s, he had visited every part of Canada except for the Western Arctic and the east side of Hudson Bay. Everywhere Innis went his methods were the same: he interviewed people connected with the production of staple products and listened to their stories.

Where did he travel?
he and a friend paddled an 18-foot (5.5 m) canvas-covered canoe hundreds of miles down the Peace River to Lake Athabasca;