from http://www.excaliburelectronics.com/history0799.html

"In the 1970's, The US Chess Federation began a campaign to convert the US to algebraic notation, which had by then become standard in nearly all countries. The arguments for the change were several: that US books would then enjoy a bigger international market; that algebraic was less ambiguous and therefore produced fewer irretrievable game scores; that algebraic took less space and more games could therefore fit into fewer pages."