WASHINGTON — President Barack Obama is designating five new national monuments, using executive authority to protect historic or ecologically significant sites – including one in Delaware sought by Vice President Joe Biden.

The White House said Obama would make the designations Monday, using the century-old Antiquities Act to protect unique natural and historic landmarks. The sites are Rio Grande del Norte National Monument in New Mexico; First State National Monument in Delaware; Harriet Tubman Underground Railroad National Monument in Maryland; Charles Young Buffalo Soldiers National Monument in Ohio; and San Juan Islands National Monument in Washington state.

The Delaware monument, commemorating the state's history and preserving about 1,100 acres near Wilmington, is the first step toward creating a national park in Delaware, the only state not included in the national park system. The project is a longtime priority for Biden, a former senator from Delaware.

"This national monument will tell the story of the essential role my state played in the history of the United States," Biden said in a statement. "I couldn't be more proud to call Delaware home."

The largest site is Rio Grande del Norte in New Mexico, where Obama will designate nearly 240,000 acres for protection. The site includes wildlife habitat valued by hunters and anglers; rafting, camping, and other recreation, and is prized by the region's Hispanic and tribal groups.

Advocates say the new monument in New Mexico, to be run by the U.S Bureau of Land Management, will contribute an estimated $15 million a year in economic benefits to the area.

The San Juan Islands monument off Washington's northwest coast includes roughly 1,000 acres of public land already managed by the BLM. Supporters say the designation will protect important cultural and historical areas and safeguard natural areas used for recreation and other purposes.

The Arlington, Va.-based Conservation Fund donated property on Maryland's Eastern Shore to the National Park Service to help tell the story of Tubman and the Underground Railroad. Tubman escaped slavery at age 27 but returned to Maryland's Dorchester and Caroline counties to help slaves escape to the North.

The Charles Young monument near Xenia, Ohio, recognizes and celebrates Col. Charles Young, a West Point graduate who was the first black national park superintendent. Young was the highest-ranking black officer in the U.S. Army until his death in 1922.

The new monuments would be the first designated by Obama in his second term. Obama created four national monuments in his first term: The Cesar E. Chavez and Fort Ord national monuments in California; Fort Monroe National Monument in Virginia; and Chimney Rock in Colorado.

Supporters called the monument designations especially important at a time of partisan gridlock over wilderness issues. No new wilderness areas were approved in the last Congress, the first time lawmakers have failed to create new wilderness since the 1960s.

"Understanding that Congress is broken, The Wilderness Society is very pleased to see President Obama taking important steps toward putting conservation on equal ground with energy development," said Jamie Williams, president of The Wilderness Society. "Protecting our lands and waters can't wait."

The New Mexico project in particular is crucial, Williams and other environmentalists said, because it includes some of the most ecologically significant lands in the state, most notably Ute Mountain, which towers over the region and provides habitat for the elk, bald eagle, peregrine falcon, great horned owl and other species.

The monument designations follow a call from former Interior Secretary Bruce Babbitt to put conservation on equal ground with energy development on public lands. Babbitt said in a speech last month that for every acre of public land leased to the oil and gas industry, an acre should be permanently protected for future generations.

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