Aerosol particle hygroscopicity is a key indicator in determining the aerosol water content (AWC) of a particle. As sulfate emissions decrease, other particle components such as nitrate and organics constitute a greater proportion of particle mass and become an increasingly important driver for determining particle hygroscopicity. However, there remains large uncertainty and limited field evidence quantifying how nitrate, sulfate, and organics determine particle hygroscopicity and AWC. This study aims to expand on the role that nitrates and organics have in determining particle hygroscopicity and AWC by using field measurements from the Tracking Aerosol Convection Interactions Experiment (TRACER) campaign in Houston, TX, conducted from 2021 to 2022 at two concurrently measured field sites. This field data is supplemented with model output from GEOS-Chem, which is used to inform the thermodynamic models ISORROPIA-II and E-AIM-IV to determine the hygroscopicity parameter (κ) and AWC of aerosol particles and their controlling factors. Nitrate is found to be the largest chemical factor influencing AWC. Organics must be included to accurately calculate κ, and doing so closes a measurement-model gap of 0.2 ± 0.1 that arises from inorganics-only estimations. Differences of less than 0.1 µg m-3 in nitrate concentrations result in differences in the AWC of up to 7 ± 4 µg m-3. These results add evidence to the growing importance of nitrate and organics in determining AWC and κ, with implications for understanding cloud droplet formation and subsequent interactions.