[2][3] The route crosses into North Woodbury Township in Blair County, where it passes through more farmland prior to heading through the residential community of Curryville.

From here, PA 866 continues through open farm fields with some homes, passing to the west of Altoona–Blair County Airport.

The road heads north-northeast into the borough of Martinsburg and becomes South Market Street, passing homes and a few businesses.

In the commercial center of town, the route crosses PA 164 and becomes North Market Street, heading past more residences.

At Point View, the route curves to the west and enters Frankstown Township, heading southwest to its northern terminus at US 22.