Environment

Climate: Mostly temperate, but tropical in Hawaii and Florida and arctic in Alaska, semiarid in the Great Plains west of the Mississippi River, and arid in the Great Basin of the Southwest

Total Number of Wetlands on Nonfederal Land and Water Areas by Land Cover/Use and Farm Production Region (2003) — 110,760,000 acres. Threatened and Endangered Wildlife and Plant Species (2006): Mammals — 357; Birds — 273; Reptiles — 118; Amphibians — 32; Fishes — 149; Snails — 37; Clams — 72; Crustaceans — 22; Insects — 49; Arachnids — 12; Plants — 748.

Did you know?
First national celebration of Earth Day was April 22, 1970.

First national park was the Yellowstone National Park in Wyoming, authorized March 1, 1872, by an act of Congress. Additional grants of land to Yellowstone Park were made in Wyoming, Montana, and Idaho.

First conservationist of note was naturalist John Muir; he founded the Sierra Club and campaigned successfully for the establishment of protected national parks and forests. Muir Woods National Monument (California) and Alaska's Muir Glacier honor him.

In 1972, astronauts on board Apollo 17 captured the first full view of Earth suspended in space, exposed in full sunlight. Amid a growing awareness of environmental concerns, the "Blue Marble" photograph became a symbol of the planet's fragility in the cold vast blackness of space. More than 30 years later, the National Aeronautics and Space Administration (NASA) receives more requests for this photo than any other, and the agency suggests that it could be the most frequently reproduced photograph of all time.