According to MapleLeafWeb.com, the maple leaf has come to be a symbol of Canada because the sugar maple is only found in Eastern Canada. The first documented use of the maple leaf as a Canadian symbol was in 1860, when it was used on the badges of the Prince of Wales Royal Canadian Regiment. It was then featured on all Canadian coins from 1876 until 1901.
The maple leaf has been used as a Canadian symbol in many ways throughout history. It was displayed on the shirts of Canadian athletes competing in the Olympic Games in 1904, and it was displayed on soldiers' caps and badges during World War I and World War II. MapleLeafWeb.com also states that the Canadian shield was revised to feature the maple leaf in 1921.
According to History.com, the maple leaf became an even better-known symbol of Canada when it was included in the Canadian flag's design on Feb. 15, 1965. Prior to this date, Canada flew a flag that was bright red in color with a British Union Jack in the upper left-hand corner and a crest on the right-hand side. Parliament voted to adopt a new flag design in December of 1964, and several months later, the maple leaf flag was born.