75 Pa.C.S. § 3321: Vehicle approaching or entering intersection.

(a) General rule.--When two vehicles approach or enter an intersection from different highways at approximately the same time, the driver of the vehicle on the left shall yield the right-of-way to the vehicle on the right.

(b) Exception.--The right-of-way rule established in subsection (a) is not applicable:

(1) on through highways, where the traffic on the through highway shall have the right-of-way;

(2) on limited-access highways, where the traffic on the limited-access highway shall have the right-of-way;

(3) in traffic circles, where the traffic in the traffic circle shall have the right-of-way; and

(4) as otherwise provided in this part.