The open access (OA) publication movement aims to present research literature to the public at no cost and with no restrictions. While the democratization of access to scholarly literature is a primary focus of the movement, it remains unclear whether OA has uniformly democratized the corpus of freely available research, or whether authors who choose to publish in OA venues represent a particular subset of scholars—those with access to resources enabling them to afford article processing charges (APCs). We investigated the number of OA articles with article processing charges (APC OA) authored by 182,320 scholars with known demographic and institutional characteristics at American research universities across 11 broad fields of study. The results show, in general, that the likelihood for a scholar to author an APC OA article increases with male gender, employment at a prestigious institution (AAU member universities), association with a STEM discipline, greater federal research funding, and more advanced career stage (i.e., higher professorial rank). Participation in APC OA publishing appears to be skewed toward scholars with greater access to resources and job security.