River networks are dynamic conveyors and processors of particulate material, commonly quantified as total suspended solids (TSS) and further characterized by particulate carbon (C), nitrogen (N), and phosphorus (P) content. The transport and processing of these materials play key roles in in-stream biological and biogeochemical processes. However, understanding of the drivers of particulate material content and transport is limited, especially at large geographical scales. Here, we expand our understanding of drivers of particulate material at the continental scale by using long-term data collected from the National Ecological Observatory Network (NEON). The NEON dataset includes regularly collected particulate chemistry data from 26 established NEON aquatic river and stream sites across the United States and Puerto Rico. At each site, we first examined relationships between TSS and concentrations of particulate C, N, and P using high-frequency turbidity data. We then leveraged additional site data, including land use and land cover, high-frequency sensor data, and continuous discharge to examine and enhance our models to ascertain the main drivers of particulate material composition and transport across the US. Our initial results demonstrate that TSS and all three elemental concentrations have significant relationships with turbidity at roughly half of the sampling sites. These initial results enhance our understanding of the driving forces of particulate material in river networks and highlight the use of large-scale sensor and sampling networks to advance the study of riverine biogeochemistry.