|Horseshoe Curve-1966. Here is an original photo that I took at the Pennsylvania Railroad's Horseshoe Curve near Altoona, Pennsylvania, during early May of 1966. Shown here (R to L) are PRR engines #5789, #5769, and #5765. All are EP-22's built by EMD in 1952 and rated at 2,250 horsepower each. They are pulling an eastbound mail/express train. Note the engineer inspecting his train!