The Allegheny Southern Railway (AAR: ASRW) was a briefly-lived Pennsylvania shortline that served southern Blair County from 1982 through 1984. The ASRW operated, under contract, the Morrisons Cove Railroad, which had been formed in 1982 to maintain service on the southernmost six miles of Conrail's Morrison Cove Secondary. This segment, with a low-density agricultural traffic base, was abandoned by Conrail earlier in the year after years of declining traffic and revenue.

Conrail's abandonment of the branch came as no surprise. This portion of the Morrison Cove Secondary had been targeted for abandonment years earlier by Penn Central. By the 1980s however, deregulation and the Northeast Rail Service Act of 1981 made it far easier to abandon low-profit rail lines. Rail Management Services (RMS), of Syracuse, NY, was commissioned by a local economic agency to develop a plan for sustained operation of local branches facing abandonment.

Option A of the RMS Report suggested operation of the branch from Milepost 18.2, south of Roaring Spring, to Martinsburg and Curryville, Milepost 24. Interchange with Conrail would be established at Milepost 17.2, at Roaring Spring, requiring one mile of trackage rights. Members of the local agricultural industry, long reliant on rail, followed Option A when forming the Morrisons Cove Railroad to preserve service on the line. RMS was given the contract to operate the line, forming the ASRW as a subsidiary of their Ontario and Eastern Railroad (AAR: ONER) to do so.

The railroad met with mixed success. A desparately needed track rehabilitation stabilized the railroad's infrastructure, which had long been ignored by previous owners. The Morrisons Cove Railroad, however, found the cost-plus contract with RMS to be unsatisfactory. At the beginning of 1985, the Everett Railroad (AAR: EV) gained the contract to operate the Morrisons Cove Railroad in place of the ASR, an arrangement that continues to this day.