Forests in the United States cover over 765 million acres of land, comprising roughly one-third of the country’s total area. These ecosystems provide functions like regulating water cycles, purifying air, and storing carbon that influences global climate patterns. Understanding the magnitude and condition of this resource requires a continuous national accounting effort to determine not just the total acreage, but the actual number of individual trees. This quantification is necessary for managing forest health and ensuring long-term stability.
The Current National Tree Count
The total number of trees is approximately 96.6 billion, according to the U.S. Forest Service. This figure counts trees on forest land, which is defined as land that is at least one acre in size and has a minimum of 10 percent tree canopy cover. The official count includes only trees that measure at least five inches in diameter at breast height (DBH). This measurement is standardized at four and a half feet above the ground, serving as a benchmark to exclude smaller saplings and seedlings from the final population estimate.
How the National Forest Inventory is Conducted
The national tree count is the result of the U.S. Forest Service’s Forest Inventory and Analysis (FIA) program, which acts as a continuous, nationwide census. The program uses a probabilistic sampling design relying on a network of over 355,000 permanent field plots distributed across all forested land. Field crews visit these plots on a rotating basis, remeasuring trees and collecting data on species, size, and health. This field data is combined with information derived from two decades of satellite imagery and aerial photographs. This allows the FIA to generate statistically reliable estimates about the status and trends of the forest resource.
Trends in US Forest Cover Over Time
The stability of the nation’s forest cover is a recent historical development. Before European settlement in 1630, an estimated 1.023 billion acres of the land was forested. Forest cover reached its lowest point around 1920, dropping to approximately 721 million acres after extensive clearing for agriculture and industrial expansion. Since then, reforestation programs and stabilization efforts have stabilized the overall acreage. On timberland, the country currently grows nearly twice the volume of wood it removes annually, despite localized losses. However, the standing population faces increasing threats from natural disturbances, with average annual mortality for large trees estimated at 1.2 billion due to factors like wildfires, pests, and disease outbreaks.
Geographic Distribution and Density
The national tree population is not distributed uniformly, with variations in density and type across major regions. The Southern United States holds a large share of the productive forest, containing about 40 percent of the nation’s timberland and earning the name of the country’s “wood basket.” Forests in the East and South are generally characterized by high density and are often privately owned. In contrast, the Western United States contains a larger proportion of publicly owned land, where forests are often restricted to montane and high-elevation regions. While the highest concentrations of very large trees, such as the Douglas-fir and Giant Sequoia, are found along the Pacific coast and in the Sierra Nevada, the overall density of forest cover in the arid interior West is considerably lower than in the continuously forested East.