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 Río 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.