A recent study with native German speakers finds that acoustic properties of speech associated with biological sex may also vary within-sex as a function of gender identity, defined gradiently along continuous scales of self-reported masculinity/femininity [M. Weirich and A. P. Simpson, “Gender identity is indexed and perceived in speech,” PLoS One 13(12), e0209226]. In particular, Weirich and Simpson find that men who rate themselves as more feminine produce speech with somewhat more female-like characteristics, such as higher mean f0 and larger vowel space area (VSA) relative to men who rate themselves as less feminine. In the present study, we investigate whether such gradient measures of gender identity have a comparable relationship to acoustics in American English. Recordings of read speech produced by 74 native speakers from metropolitan New York City (38 females, 36 males) were analyzed with respect to VSA and spectral properties of the sibilant fricative /s/. Gradiently defined gender identity was, as in Weirich and Simpson (2018), estimated for all speakers using two established measures of self-reported femininity. We report findings related to VSA and /s/ for both male and female speakers, and discuss the implications for the role of sex and gender in phonetics research.