Methodology and Interpretation

Population density (individuals/km2)
Population density is calculated by summing number of people living in the reporting unit and dividing by the reporting unit area. Where census units are not completely contained within the reporting unit, population is apportioned by area. High population densities are generally well correlated with high amounts of human land uses, especially urban and residential development. Large areas of development often involve substantial modification of natural vegetation cover that may have substantial effects on wildlife habitat, soil erosion, and water quality.

Quantile: Each class contains an approximately equal number (count) of features. A quantile classification is well-suited to linearly distributed data. Because features are grouped by the number within each class, the resulting map can be misleading, in that similar features can be separated into adjacent classes, or features with widely different values can be lumped into the same class. This distortion can be minimized by increasing the number of classes.

Metric input GIS data:

• United States Hydrologic Units (8-digit HUCs) - Metadata

• United States Coastal Change Analysis Program (CCAP) - Metadata

• United States Census 2000 (c2k) - Metadata

• United States Roads (Wessex / GDT) - Metadata