The GE C44-9W is a 4,400 hp (3,281 kW) diesel-electric locomotive built by GE Transportation Systems of Erie, Pennsylvania. Keeping in tradition with GE's locomotive series nicknames beginning with the "Dash 7" of the 1970s, the C44-9W was dubbed the Dash 9 upon its debut in 1993. The design has since proven popular with North American railroads. Because of more stringent emissions requirements that came into effect in the United States on January 1, 2005, the Dash 9-44CW has been replaced in production by the GE ES44DC.
BNSF Dash 9 #4723 is featured as a drivable locomotive in Microsoft Train Simulator and the actual Dash 9 has stickers on its cab noting this, and Dash 9's are also featured as drivable locomotives in RailWorks 3 and Trainz Simulator.
The BNSF AC44C4M is a GE C44-9W rebuilt with AC traction motors and an A1A-A1A wheel arrangement. The internal controls are similar to those of the newer GE ES44C4.
Norfolk Southern also is experimenting with converting their Dash 9-44CW units to A.C. the first unit, (8900) is still being tested. As of November 2015, the rebuild have been officially classified as "AC44C6M."
Most have been repainted or patch-renumbered into the Union Pacific Railroad's rosters. Two Dash 9 locomotives, #8646 and #8701, which remained in service on the UP with full C&NW paint and reporting marks once resided at the Illinois Railway Museum in Union, IL. The locomotives are in storage at the museum, but they are still owned by the railroad, so they can be called back into service at any time. Three more in C&NW paint are still in service but are patched by UP (Numbers 9696, 9798, and 9771). In early 2017, the "Twins", as #8646 and #8701 are nicknamed, were brought back into service.