I had thought "median" was an ancient term, but it was popularized with

the 1900 census. OED has the March 1900 _Boston Transcript_ citation, but

doesn't give the date, nor page number. This is from the Asbury Park Daily

Press, 15 March 1900, pg. 5, col. 4:


New Word Coined to Supplant Average and Center.

A new word seems destined to come into use with the census of 1900 and

the discussions that will follow the interpretation of its results, says a

Washington correspondent of the Boston Transcript. The word is "median." It

ought to displace average and center for the greater number of ordinary consus

uses, since the notion of "average" which most people have is really expressed

by "median," while "average" means quite another thing. There is room in our

terminology for both terms, just as we distinguish between plurality and

majority to good advantage in discussing election returns. The average age of

the population of the United States, for example, is 25 years; the median age

is 21 years. The latter means the point at which there are as many people

above as below. (...)