Thanks for the quick reply. I've got a (new to me)15" MacBookPro, early 2011, and I'm running OS X 10.9.5, which I downloaded yesterday (so Mavericks is also new to me). Unfortunately, I'm having no luck with your suggestions: At full screen and the most extreme possible zoom level, (with Zoom menu items or with mouse wheel) the street name caps are about 1/16", and the small letters are about half of that. Of course, at less extreme zoom, the letters are smaller. Adding further injury to this insult and injury, the letters are grey rather than black, and the font is whatever you call the opposite of bold.
I find no other relevant setting anywhere in the menus, and the Maps drrop-down has no Preferences item.
On this gorgeous 15" screen, under ideal lighting conditions, I can just barely read this map. On a tablet or phone, driving, on a bright sunny day, ... no chance in ****. Is it possible that Apple botched the design this severely? Isn't there a secret command hiding somewhere?
But I really do appreciate your taking the time and trouble of sending me suggestions which were exactly on topic, and might have worked.