In contrast to free-living species, theory governing parasite abundance is lacking, partly due to a lack of quantitative parasite population data. Parasite abundance is controlled by its niche, which is partly environmental and partly host habitat. For macroparasites, abundance is dictated by host abundance, parasite intensity, parasite prevalence, and an ability to survive and develop outside of the host. The natural variation in parasite abundance has implications for infection pressure in host species and understanding what drives this variation is an important knowledge gap. In this study we used a 30-year longitudinal study of white-tailed deer with intensity data scored for 16 macroparasites in 2364 deer sampled in 180 US counties to ask (i) which component of parasite abundance most strongly correlates with abundance itself? (ii) How consistent are patterns across different parasite species? (iii) And what environmental factors explain geographical variation in parasite abundance? To answer these questions, we estimated parasite abundance for each county as the product of parasite prevalence, parasite intensity, and deer abundance. We calculated rank correlation coefficients for each component of parasite abundance with abundance itself. Lastly, we performed statistical modeling to relate county-level abundance to underlying environmental data obtained from WorldClim. We found parasite intensity to be most positively and significantly correlated with parasite abundance, which suggests that attaining high intensity infections in hosts is most important for achieving high parasite abundance. Furthermore, temperature seasonality constrains the abundance of several parasite species; however, this pattern is parasite specific. Collectively, this illustrates that parasite abundance is governed by both host and non-host components of its niche.