First-generation college students (FGCS), defined as students whose parents did not earn a baccalaureate degree, encounter distinct obstacles navigating academia. Barriers faced by FGCS, including lack of financial security, lower sense of belonging, and inadequate mentorship, are often compounded by the intersection of other marginalized identities. As such, efforts to improve diversity, equity, and inclusion can and should include FGCS. To better support FGCS, first we must fully understand who they are, where they are pursuing degrees, what they choose to study, and their representation in the geosciences. We use over 40 years of data to explore the demographics and field of study of FGCS in U.S. institutions. We observe that FCGS have outnumbered non-FCGS at the undergraduate level since data collection began in the 1990's. At the doctoral level we present data from 1974-2016 that show that although non-FGCS have outnumbered FGCS since the 1990's, most doctoral graduates of color continue to be FGCS. Our data also show that in 2016 over 61% of all undergraduates receiving a bachelor's degree across all fields were FGCS, 54% of physical science undergraduates were FGCS, and yet only 25% of those in the geosciences were FGCS. Out of the various fields analyzed, the geosciences have the lowest percentage of FGCS at the undergraduate and doctoral level. This begs the question, why are FGCS yet another markedly underrepresented group in the geosciences? Here we begin to address this question and provide guidance for how to reduce barriers to FGCS inclusion in the geosciences.