Was 俺 ever gender-neutral?

Question

I've heard elderly women in Japan referring to themselves using 俺. This leads me to believe that the usage has changed overtime to become only used by males. Did 俺 used to be gender-neutral?

Answer 1

According to WWWJDIC via Rikaichan:

俺 おれ、 だいこう、 ないこう (pn,adj-no,male) I; me (rough or arrogant-sounding first-person pronoun, formerly also used by women); (P)

So it seems that it used to be a gender-neutral noun.

Answer 2

Quoting Wikipedia:

「おれ」は「おのれ」の転訛で、鎌倉時代以前は二人称として使われたが次第に一人称に移行し、江戸時代には貴賎男女を問わず幅広く使われた。明治以降になると共通語では女性の使用者はほぼいなくなったが、東北地方を中心に方言では根強く残っている。愛知県西三河地方でも農業地区では女性の一人称として平成の今日に至っても使用されている事例がある。

また、アクセントは平板型（「れ」の方が高く、それとほぼ同じ音高で後の語が開始する）が一般的であるが、一部地域[どこ?]では「お」にアクセントを付けて使用することもある。

西日本では年をとると「わし」に移行することが多い。特に広島などでは「俺」は気取った一人称とされ、通常の場ではあまり使われない。

Translation:

おれ, which originally came from おのれ, used to be used as a second-person pronoun (like “you”) before the Kamakura period (1185–1333). However, it gradually became used to refer to oneself and was used by men and women of various backgrounds widely in the Edo period. In the Meiji period, most women stopped using it in the standard dialect, but its usage remained strong in local dialects mainly in the Tohoku region. Also, in the west Mikawa region of Aichi prefecture, it is still used today by some women to refer to oneself in local farming areas.

Generally the [平板型]{へいばんがた} accent is most commonly used. However, in certain regions, an accent is put on the お.

In western Japan, many people refer to themselves as わし when they get older. In Hiroshima especially, the use of おれ is considered to be arrogant and is not used often.