The Conservation Fund announced Thursday that it has donated 254 acres near Brandywine Creek in Delaware County to First State National Historical Park on the Delaware-Pennsylvania border in a landscape of rolling hills, meadows, and wetlands captured and made famous in paintings by Andrew Wyeth.

“We are thrilled to accept this land donation from the Conservation Fund,” Cinda Waldbuesser, superintendent of First State National Historical Park, said in a statement. “The addition of this land to the park’s Brandywine Valley Unit adds many new miles of trail and bucolic landscapes for park visitors to enjoy.”

Established in 2013 by the Obama administration, it is the first national park located in Delaware, and also crosses the state line into Delaware County. It officially became the country’s 400th national park in 2015.

Though it includes historical sites in Delaware, the heart of the park is a 1,100-acre tract known as the Woodlawn property used for hiking, cycling, running, and boating. About 300 acres of that tract are in Pennsylvania. Now, an additional 254 acres adjacent to the park, known as the Beaver Valley property, will be added, boosting Pennsylvania’s acreage of the park in the Chadds Ford area, just west of Route 202.

Blaine Phillips, a vice president at the Conservation Fund who worked on the acquisition, said the Beaver Valley property was purchased in 2017 with an undisclosed amount of funding from Delaware’s Mount Cuba Center. The Conservation Fund transferred the property within the last month at no cost to the National Park Service.

“This purchase is important because not only does it add to First State National Historical Park, but because it is an important moment in protecting the Brandywine Valley,” Phillips said. “Countless local residents will use this property, but it also will attract visitors to the area. ... These properties are threatened and we had to step in.”

The property has a long history, serving first as traditional homeland for the Leni-Lenape people. William Penn acquired what later became the Woodlawn property from the Duke of York in 1682. Industrialist William Bancroft bought the land in the 1900s and it has been maintained as open space.

However, pressure to build continued over the decades and a developer had rights to part of the Beaver Valley property. A development of 150 homes was planned. The Conservation Fund bought the property and those rights in 2017 and opened the land to the public.

The transfer to the national park system ensures that it will remain officially protected and with much greater opportunity for public use, educational programs, trail maintenance, and parking.

“People in the community have been enjoying the beauty of the Beaver Valley property for years, so it may come as a surprise that it wasn’t actually a part of the park until now,” said Phillips, who called the addition “icing on the cake.”

A new sign welcomes visitors to the Beaver Valley section of First State National Historical Park.

Ann C. Rose, president of the Mount Cuba Center, a private foundation based in Hockessin, Del., said the “environmental and historical significance of the Beaver Valley property make it a unique cultural resource that was on the verge of being lost forever” and that integrating it into First State National Historical Park made sense to protect not only contiguous open space, but wildlife habitats.

“The Lenape Indian Tribe of Delaware commends the Conservation Fund, Mount Cuba Center, and all their patrons for an outstanding job in preserving the Beaver Valley tract,” said Dennis “White Otter” Coker, principal chief of the Lenape Indian Tribe of Delaware.