Royal Oak, residential city (1990 pop. 65,410), Oakland co., SE Mich., a suburb of Detroit; settled c.1820, inc. as a city 1921. There is metal forging and the manufacture of automotive and computer parts. Royal Oak's population decreased considerably in the late 20th cent. The Detroit Zoological Park is there.
"Royal Oak." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (September 19, 2018). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/royal-oak
"Royal Oak." The Columbia Encyclopedia, 6th ed.. . Retrieved September 19, 2018 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/royal-oak