Peatlands occur in cold temperate climates with high humidity. They mostly occur in the northern hemisphere, where evaporation (water loss from the water surface) and transpiration (water loss from plants) are less than precipitation. Large expanses of peatlands occur in Alaska and Canada as well as in Scandinavia, Eastern Europe, and western Siberia. Smaller peatlands occur in the northeastern and north-central U.S., the Appalachian Mountains, and the Mid-Atlantic Coast region. There are an estimated 865 million acres of peatlands in the world. About one-third of this total occurs in the U.S. and Canada.

Bogs found in the Atlantic coastal plain from Virginia to Florida are called pocosins. Dominated by evergreen shrubs and trees, pocosins are found in broad, flat uplands far from streams. Unlike northern bogs there is usually no standing water in pocosins, though soil stays saturated for much of the year. Occasional drying of the soils in late summer historically lead to natural fires. Fires are ecologically important because they increase the diversity of shrub types in pocosins.