The National Park Service is celebrating its big birthday this week with a nationwide celebration.

One hundred years ago Thursday, President Woodrow Wilson signed the act creating a federal bureau to oversee the nation's growing number of parks and monuments.

A century later, there are more than 400 National Parks covering 84 million acres across the country. More than 300 million people visit the sites every year, according to federal statistics.

To celebrate its 100th birthday, the National Park Service is offering free admission and fee waivers at many of its parks from Thursday to Sunday. The New Jersey sites waiving fees this week include Thomas Edison National Historic Park in West Orange and Morristown National Historic Park, the park service said.

New Jersey is home to a dozen parks, trails and other sites that are either overseen by or considered part of the National Park Service. The New Jersey sites had more than 4.2 million visitors last year and contributed $135.8 million to the local economy, according to federal estimates.

The National Park Service sites in New Jersey are:

Appalachian Trail National Scenic Trail

Part of the 2,180-mile trail passes through New Jersey. The 72-mile stretch begins at the Delaware Water Gap, continues along the Kittatinny Ridge to High Point and along the New York border. Visitor can take day hikes or walk the entire New Jersey portion.

Delaware Water Gap National Recreation Area

The 70,000-acre park is along the Delaware River on both the New Jersey and Pennsylvania sides. Visitors can paddle on the river, fish in the trout streams or hike the ridges and valleys.

Ellis Island (Part of the Statue of Liberty National Monument)

Nearly 12 million immigrants passed through Ellis Island on their way to a new life in the United States. The island now serves as a museum and a monument to the immigrant experience.

Sandy Hook/ Gateway National Recreation Area

The Gateway National Recreation Area includes 27,000 acres along the ocean and bays in New Jersey, Brooklyn, Queens and Staten Island. New Jersey's portion is Sandy Hook, the popular swimming, hiking and biking park at the northern end of the Jersey Shore in Monmouth County.

Great Egg Harbor River

Designated a federal park site in 1992, the National Park Service helps oversee the 129-mile river system in the Pinelands National Reserve.

Lower Delaware National Wild and Scenic River

The lower part of the Delaware River became part of the National Park System in 2000.

Morristown National Historic Park

George Washington and the Continental Army spent the winter of 1779 and 1780 encamped in Morristown. The site includes a museum and library devoted to pre- and post-Revolutionary America.

New Jersey Coastal Heritage Trail

The trail stretches 300 miles along the Jersey Shore and includes stops at lighthouses, historic villages and boardwalks. Designed for driving, the trail stretches from Raritan Bay in Perth Amboy, along the shore to Deepwater near the Delaware Memorial Bridge.

New Jersey Pinelands National Reserve

The Pinelands includes over a million acres of forests, wetlands and farms in seven of New Jersey's southern counties.

Paterson Great Falls National Historical Park

New Jersey's newest National Park site is the towering waterfall in one of the state's largest cities. The falls are surrounded by the remnants of mills and factories in the industrial city.

Thomas Edison National Historical Park

Thomas Edison's home and laboratory in West Orange are preserved to mark the site where one of the nation's greatest inventors lived and worked.

Washington-Rochambeau National Historic Trail

In 1781, the George Washington and the Continental Army joined forces with General Jean-Baptiste de Rochambeau and the French Army joined forces and marched from Rhode Island to Virginia to fight the British. Their route was designated a National Historic Trail in 2009. The New Jersey portions pass through most of the counties in North and Central Jersey before crossing into Pennsylvania.

Kelly Heyboer may be reached at kheyboer@njadvancemedia.com. Follow her on Twitter @KellyHeyboer. Find her at KellyHeyboerReporter on Facebook.