Wasn't there just a thread on this?
Anyway, a few data points
The 1952 (British) _Good Housekeeping's Picture Cake Making_, gives a recipe for plain "macaroons" which is a meringue with ground almonds folded in, followed by recipes for "coconut macaroons," "chocolate macaroons," "peanut macaroons" etc., all also meringues with stuff added. No fillings.
The 1961 _Larousse Gastronomique_ (en anglais) gives macaroon as the equivalent of macaron, both defined as "a small round dry pastry made of almond paste, sugar and the white of an egg." These are what you may know as amaretti, which is to say the egg whites are mixed in unbeaten.
The 1961 NYT Cookbook lists "almond macaroons" but no other kind, similarly combining *unbeaten* egg white with almond paste.
Clearly at some point in the U.S. the un-meringued coconut variety became so popular as to be identical with "macaroons," resulting in the gummy, over-sweet confection Pete refers to.
If someone has different vintages of _Joy of Cooking_ lying around, that might shed more light.
And then much more recently the almond ones, or just the plain meringues, were re-introduced into the U.S. sandwiching little fillings, yuppie candy for $2 a pop.