How long has the expression 'underage woman' been in use, and is it an oxymoron?

A blog entry posted today at The Atlantic online—"The Myth of the 'Underage Woman'," by Megan Garber—argues that "underage woman" is an oxymoron:

The phrase is wrong in every sense: There is no such thing as an “underage woman.” Underage women are girls.

This led me to wonder how long the notion of "underage woman" has been floating around in English. A quick Google Books search finds instances from at least as far back as Jürgen Haller, Hormonal Contraception (1972), which includes this passage:

1. Basically, a physician must decide for himself whether or not he is willing to prescribe oral contraceptives for an unmarried and legally underage woman.

It seems very plausible that the term "underage woman" arose in connection with legal notions of a person's "age of consent"—whether with regard to marriage, access to contraceptives or abortion, sexual activity, or something else. But it is unclear to me what the original context for this expression was. Hence my questions:

1. When and in what context did the term "underage woman" originate?

2. Is "underage woman" an oxymoron, as the Atlantic blogger asserts, or is there a way to understand it as a meaningful subcategory of the much larger category "woman"?

Solution 1:

To your first question, the original context would have been legal, and I can find attestation for the exact phrase and similar phrases in the 1960s. A collocation search in the Corpus of Historical American English doesn't turn up "underage woman," but it does turn up several terms related to age-related laws, whether alcohol consumption (drinking, drinkers), sexual consent (girls, girl, brides, kids, prostitutes, sex), smoking (smoking), working (workers), or (...) underaged wizardry:

To follow usages referring to women, the earliest result for "underage (woman-like word)" comes from a 1960 Time article on laws related to sex ("More Harm Than Good?" Time Magazine, 1960/08/22.):

In North Carolina, promiscuity of an underage female can be a defense against a rape charge, but in Missouri a rape conviction is possible even when the woman involved is a professional prostitute.

Using the TIME Magazine Corpus, I found another instance from the 1960s, here from a 1963 article ("Dial S for Squalor," 1963/08/02)

The Crown's case against Ward was that he had at various times shared his Wimpole Mews apartment with Christine and Mandy, urged them and several other women to sell themselves to men of his acquaintance and to enlist other underage girls to do the same, presumably for his own profit.

As for "underage woman," the Hathi Trust has a record for the Acts of the General Assembly of the State of Georgia from 1965. Within it, "underage woman" appears four times on page 336. Sadly, the page is not accessible online, but the context suggests that the exact phrase was used in a state legislative record as early as the mid-1960s. The collocation may be possible long before that, since the notion of a woman being underage was apparently present even in the early 20th century ("Pair Travel Far; Wedded at Last," The Washington Times, June 28, 1908, p.2):

The young woman is underage. The consent of her father, who deserted his family severals (sic) years ago and whose present whereabouts is not known, could not be obtained.

It's possible an archive search could turn up even older results, but based on several archive searches, "underage woman" feels more continuously current after the 1960s.