But now one of Canada's revisionist historians is challenging that prevailing view. Having delved into Ontario's archives Dr Robert Brown has concluded it was the cities and towns, rather than rural communities, which pushed for long summer breaks.
Back in the 1840s Ontario's elementary schools took only a two-week summer holiday - plus eight days at both Christmas and Easter. But by 1860 the urban areas were leading the trend towards longer summer holidays - in the face of opposition from rural counties.
In Toronto it made sense to take a long summer break because schools were often uncomfortably hot and stuffy in July and August. But rural schools had different weather worries. "Many of the pupils, by reason of their age, the long distance from school, and the storms of the long winter, are unable to attend except in summer," one petitioner complained in 1886.
At the beginning of this century schools in rural Ontario were therefore still taking shorter summer holidays than in Toronto but they finally fell into line and accepted the standard two-month break in 1913.
Dr Brown, a research officer for Toronto District School Board, says that there is also evidence that US cities such as Detroit, Buffalo and Philadelphia introduced longer holidays before the surrounding agricultural areas. "The development of the (US) summer holiday is virtually parallel to that of Toronto, changing from year-round schooling from the middle part of the century to a two-month holiday by the late 19th century."
But he admits he is still unsure about the real rationale for long summer holidays. Cities may have seen them as a way of reducing absenteeism, a major concern in the 19th century. The elementary schools may have been mimicking the city grammar schools which had traditionally enjoyed longer holidays. But administrators may also have been responding to medical research warning that children needed time to regenerate their energy.
Dr Brown's search for the definitive answer continues.
Correspondence: Robert S Brown email@example.com