Habitat loss and fragmentation is a common conservation threat in the United States. Land in urban areas is at a premium for biodiversity preservation and historic landmarks and cemeteries are green spaces that undergo limited disturbance. Historic and sacred sites, such as those designated by historical markers and listed as cemeteries often contain remnant old growth trees, native species and potentially rare or endangered flora. Old growth trees are often considered a ‘keystone structure’, providing resources that are crucial for other species and/or a ‘foundational species’, essential in forest ecosystems providing food and shelter for wildlife. These mature trees are more prone to environmental factors such as competition with invasive plants, climatic extremes, air pollution, disease/pets and habitat fragmentation, therefore it is crucial to evaluate these historical places to assess their ecosystem service roles. A rapid decline of old foundational trees will have major impacts on the ecosystem services reported in this study. Using a citizen science survey approach and the iNaturalist smartphone app, as well as i-Tree Eco software, we surveyed trees at cemeteries and various historical places in Clinton County, NY. Tree species, diameter at breast height, tree height, percent crown dieback, as well as signs of disease, and woodpecker damage were recorded. The survey found that the most common tree species were Picea abies (Norway spruce), Robinia pseudoacacia (black locust), and Picea pungens (blue spruce). Black locust sequesters the most carbon ≈ (525 kg/yr), while Norway spruce reduces runoff (≈75 m3). Annually, mature foundational trees combined annually removed ≈ 57.03 kg ($870/yr) of pollution, stored ≈ 148.7 tons ($21,300) of carbon, ≈ sequestered 1.302 tons ($186.00/yr) of carbon, and produced ≈ 3.472 tons of oxygen. Locally, Riverside Cemetery annually sequestered the most carbon (0.4 tons), produced ≈ 1.2 tons of oxygen, and stored ≈ 1.5 tons of CO2, followed by Gilliland Cemetery. Interestingly, Gilliland Cemetery was found to be a monoculture of the invasive species black locust; more research could provide insight as to ecosystem functioning prior to the invasion. Further research is needed to help provide a stronger ecological value to these historical and sacred spaces.