The Royal Blue was the Baltimore and Ohio Railroad (B&O)'s flagship passenger train between New York City and Washington, D.C., in the United States, beginning in 1890. The Baltimore-based B&O also used the name between 1890 and 1917 for its improved passenger service between New York and Washington launched in the 1890s, collectively dubbed the Royal Blue Line. Using variants such as the Royal Limited and Royal Special for individual Royal Blue trains, the B&O operated the service in partnership with the Reading Railroad and the Central Railroad of New Jersey. Principal intermediate cities served were Philadelphia, Wilmington, and Baltimore. Later, as Europe reeled from the carnage of World War I and connotations of European royalty fell into disfavor, the B&O discreetly omitted the sobri