The ''Rainbow Special'' was a "fast train" operating over the Missouri Pacific between

Kansas City, Missouri Kansas City (abbreviated KC or KCMO) is the largest city in Missouri by population and area. As of the 2020 census, the city had a population of 508,090 in 2020, making it the 36th most-populous city in the United States. It is the central ...

, and Hot Springs, Arkansas, (later extended to Little Rock, Arkansas). The service was introduced in 1921.

References

Passenger trains of the Missouri Pacific Railroad Railway services introduced in 1921 {{US-rail-transport-stub