Travel By Numbers: US national parks

3.5

The percentage of the US surface area that is designated as national park. The 58 parks range in size from Wrangell-St Elias National Park and Preserve in Alaska, which is two-and-a-half times the size of Wales, to Thaddeus Kosciuszko National Memorial in Pennsylvania, an 80 sq m plot commemorating the life of the Polish patriot and hero of the American Revolution. All are operated by the National Parks Service, which is running National Parks Week from today until 25 April. nps.gov

150

The amount of rain in inches that falls annually on the foothills of the Olympic National Park, Washinton, making this the wettest place in mainland North America. The park also contains 73km of coastline for visitors to make a splash in. AT Kayaking offers half-day mountain biking or kayaking tours of the park from $75 (£50) per person. atkayaking.com

0.25

The distance in miles travelled each day by the vast, slow-moving body of water that runs south west from Lake Okeechobee to Florida Bay. The marshland and mangroves of Florida's Everglades National Park is the result, providing habitats for alligators, manatee and vast numbers of wading birds. Virgin Holidays offers week-long fly-drive packages to Orlando for around £540 per person in May. virginholidays.co.uk

9,000,000

The number of people who enter the Great Smoky Mountains National Park each year, making it the most visited national park in the US. The park lies on the border of North Carolina and Tennessee, and the 3,500 mile Appalachian Trail (one of the great US long-distance hikes) passes through it. appalachiantrail.org

282

The depth below sea level in feet of Death Valley, which forms part of one of nine national parks in California, and is the lowest point in the US. Summer temperatures are also extreme: the highest temperature in the western hemisphere (56.7C) was recorded here at Furnace Creek. The luxury Furnace Creek Resort operates year round, with a pool to keep you cool. Cabin rooms from $128 (£86) in the heat of the low season (May-Oct). furnacecreekresort.com

145

The average height in feet of the eruptions of water from Old Faithful Geyser, which lets off steam every 65-90 minutes in Yellowstone National Park, Wyoming. Established in 1872, Yellowstone was the first US national park. Visitors can stay at the Old Faithful Inn (open May-October), part of the "Old Faithful Historic District" which includes the geyser. Doubles from $96 (£64) per night. yellowstonenationalparklodges.com

20, 320

The height in feet of Mount McKinley, which lies within Denali National Park, Alaska. The highest mountain in North America, Mount McKinley can be seen (though not climbed) during Exodus's 16-day small-group "Alaskan Hike" trip, which costs from £2,649 per person. The next departure is 10 July. exodus.co.uk

34,005

The volume in cubic feet of "Grizzly Giant", the 25th-largest giant sequoia tree in the world and the oldest tree in Yosemite National Park, California. The park is also known for its dramatic scenery, waterfalls and population of black bears. Extranomical Adventures offers two-day Yosemite tours from San Franscisco from $210 (140) per person, including bus transport and overnight accommodation. extranomical.com

The age of Theodore Roosevelt when he died in 1919. The 26th US president had a lifelong interest in nature, and is commemorated in the Theodore Roosevelt National Park in the Badlands of North Dakota, an area Roosevelt described as being "so fantastically broken in form and so bizarre in colour as to seem hardly properly to belong to this earth." The park is divided into two main areas approximately 70 miles apart, with the remains of Roosevelt's own Elkhorn Ranch between them. ndtourism.com