I've read (unsure if factual, can't find a source right now) that the plane's original designation was to be RS-71 (because reconnaissance). At some point, in

I've read (unsure if factual, can't find a source right now) that the plane's original designation was to be RS-71 (because reconnaissance). At some point, in a speech or introduction, some high ranking official misread that as SR-71, and after that all documentation was updated to show this new designation.