Microplastics (i.e., particles < 5 mm) are ubiquitous pollutants. Microplastics include a diverse suite of materials, which vary by polymer type, shape, and chemical additives. Sources of microplastics to rivers include wastewater, stormwater, atmospheric deposition, and industrial effluent. The latter includes ‘nurdles’ or pre-production pellets, commonly found as 2-3 mm disks. About 10 trillion nurdles are littered annually. In marine sites, nurdles are dispersed long distances, ingested by animals, and leach chemical additives. However, they are among the least well-studied types of microplastics in freshwater ecosystems. There are no standard protocols for quantifying their density in rivers and little is known about their distribution. Our objective was to locate potential nurdle sources and quantify their distribution in rivers throughout northeastern Illinois. We generated a map of sites by identifying plastic manufacturing facilities and their proximity to rivers. At several potential sources, we quantified nurdle abundance up- and downstream. We used four approaches, depending on nurdle density and environmental conditions: quadrats, nets, passive samplers, and visual surveys. We found nurdles at almost all study sites, regardless of proximity to potential sources. While density and assemblage were highly variable within and among study sites, nurdles were most abundant in shallow waters with organic matter accumulations (i.e., riparian vegetation and boat launches). Our results show nurdles are common throughout the region and likely widely dispersed from potential sources. These preliminary data will be integrated with additional measurements to inform standardized protocols for nurdle quantification in rivers. Results will inform emerging policies for nurdle pollution reduction.