|Operators|Named trains|Destination|Year begun|Year discontinued|
|---|---|---|---|---|
|Baltimore and Ohio|Capitol Limited|Chicago, Illinois via Washington, D.C. and Pittsburgh, Pennsylvania|1923|1958*|
|Baltimore and Ohio|Metropolitan Special|St. Louis, Missouri via Washington, D.C. and Cincinnati, Ohio|ca. 1920|1958*|
|Baltimore and Ohio|National Limited|St. Louis, Missouri via Washington, D.C. and Cincinnati, Ohio|1925|1958*|
|Baltimore and Ohio|Royal Blue|Washington, D.C.|1890|1958|
|Central Railroad of New Jersey|Blue Comet|Atlantic City, New Jersey|1929|1941|
|Reading Railroad with the Central Railroad of New Jersey|Crusader|Philadelphia, Pennsylvania|1937|1967|
|Reading Railroad with the Central Railroad of New Jersey|Harrisburg Special|Harrisburg, Pennsylvania|||
|Reading Railroad with the Central Railroad of New Jersey|Queen of the Valley|Harrisburg, Pennsylvania||1967|
|Reading Railroad with the Central Railroad of New Jersey|Wall Street|Philadelphia, Pennsylvania|||
|Reading Railroad with the Central Railroad of New Jersey|Williamsporter|Williamsport, Pennsylvania|||

Question: what is the difference (in years) between when the royal blue began and the year the crusader began?
Answer: 47