Urban forests provide many benefits to society, including moderating climate, reducing building energy use and atmospheric carbon dioxide, improving air and water quality, mitigating rainfall runoff and flooding, enhancing human health and social well-being, and lowering noise impacts. However, various natural and anthropogenic forces (e.g., tree planting and removal, development, natural regeneration, storms, insects and diseases) are constantly altering the urban forest and consequently affecting the benefits and values derived from the forest. To sustain urban forests as a national resource to improve human health and well-being, it is important to understand how this resource and it benefits are distributed across the United States and how it is changing. To this end, Northern Research Station scientists combined field data from urban areas, photo-interpretation of tree cover, and modeling of urban forest benefits to assess urban forest benefits and change in urban tree cover for all U.S. States. The annual benefits derived from the Nation’s urban forests due to air pollution removal, carbon sequestration, and lowered building energy use and consequent altered power plant emissions are estimated at $18.3 billion. However, this important resource, which contains about 5.5 billion trees and varies in the amount tree cover across the United States, is declining at a rate of about 138,000 acres per year, which corresponds to approximately 28.5 million trees per year.