Alapocas Run State Park, Delaware state park in Wilmington, US.

Alapocas Run State Park is a Delaware state park in New Castle County that runs along Brandywine Creek, featuring wooded trails, athletic fields, a natural rock climbing wall, and the historic Blue Ball Barn. The land rises and dips across forested slopes, open meadows, and stream corridors that cut through the property.

Alapocas Run began as a 123-acre city park called Alapocas Woods. In 1910, while Alfred I. du Pont was building his Nemours estate, William Poole Bancroft persuaded him to transfer land between Nemours and Brandywine Creek to Wilmington; Bancroft donated part of his own land and, as president of the Wilmington Park Commission, later helped pay to pave Alapocas Road. The park became part of Wilmington State Parks in 1998 and was dedicated as a state park in 2002 after the Blue Ball Project added about 152 acres.

The Blue Ball Barn, now the park visitor center, displays the Delaware Folk Art Collection: over 120 works by 50 local artists. Its name comes from a late-18th-century tavern nearby, where a blue ball on a pole was raised to signal illiterate stagecoach drivers that passengers awaited and lowered to let coaches pass.

The trails cross uneven ground and can be wet near the streams, so sturdy footwear is a good idea before heading out. The park connects to the Northern Delaware Greenway Trail system, which makes it easy to extend a walk into neighboring green areas.

The climbing wall occupies the remains of a granite quarry that operated from 1870 to 1938. Its stone built the Brandywine Park walls, the tower at Rockford Park and the National Harbor of Refuge. The quarry is also used for school programs on earth sciences.