This study extracted, quantified, and characterized microplastics (MPs, plastics <5mm) from two soil depths (0-9 cm and 9-18 cm) surrounding sites where solid waste is openly dumped and burned. Open dumping and burning is a non-standardized waste management practice utilized throughout the globe, including remote, underserved rural, and Native communities of the United States. Open burning unevenly incinerates solid waste and generates partially combusted plastic pieces which are potentially more prone to MP generation than their non-burned counterparts. Furthermore, incomplete combustion likely modifies the chemical and physical features of MPs which may lead to the release of derivatives, constituent monomers, flame retardants, or additives used during plastic fabrication. The objectives of this study were to 1) quantify the occurrence of MPs in soils surrounding open dump and burn sites, 2) evaluate the polymer type, and functional chemistry of detected MPs and 3) elucidate any trends in MPs abundance, polymer size, polymer type, and surface chemistry in relation to soil physiochemical characteristics, depth, or site history and use. We sampled a single-family open burning site located in rural Tuttle, Oklahoma (Rural Oklahoma Burn Site) and two community-wide sites in Crow Agency, Montana (Crow Agency Burn Site and Lodge Grass Dump Site). Across the three sites MPs concentrations ranged from 900-35,000 particles kg-1 soil in the 0-9 cm soil profile and 12,300 to 69,200 particles kg⁻¹ soil in the 9-18 cm profile. The highest particle concentration was observed at Lodge Grass Dump Site. Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy results indicated that polyethylene was the dominant polymer in the 0-9 cm depth followed by polypropylene. Rayon, polystyrene, polyvinyl chloride, acrylic, and polyester were also commonly detected. Similar polymer relative abundance was observed in the 9-18 cm profile, with the addition of polyester and monomers such as olefins. Particles detected with fluorescence microscopy and automated particle counting were smaller in the 9-18 cm profile than the 0-9 cm profile of the Rural Oklahoma Burn Site, while the inverse was found at Lodge Grass Dump Site. Many of the MPs examined with ATR-FTIR displayed signs of extensive oxidation and were thus mis-identified by stock spectral search libraries. Upon comparison with in-lab generated thermally oxidized plastic spectra, search results were improved and particles were more accurately identified. These results indicate that open dumping in burning is a source of oxidized MPs in the terrestrial environment. The observed vertical distribution of MPs suggests that smaller particles may travel further into the soil profile over time, which begins to inform our understanding of the transportation and fate of MPs in the soils surrounding open dumping and burning sites. Centrally, these findings inform the affected communities, providing quantitative and qualitative insight that can be used in risk assessment, decision making, and resource acquisition and allocation.