Does anyone know why men with long hair weren't allowed into Disneyland until the 1960's?

Up until the late 1960s, long-haired male visitors to Disneyland were stopped at the park gates by cast members who politely informed the hirsute guests that they did not meet the standards of Disneyland's ("unwritten") dress code and therefore would not be allowed to enter the park.
Disney's philosophy was that customers preferred park workers to be wholesome and well-scrubbed, and some of the same appearance restrictions they placed on their employees were applied to other park guests as well. (For example, Jim McGuinn, future founder of the Byrds, was turned away from Disneyland in 1964 merely for sporting a Beatle cut, and at one point women wearing halter tops were also prohibited from entering the park.)

http://www.snopes.com/disney/parks/longhair.htm

http://www.snopes.com/disney/parks/longhair.htm