The following is taken from the website: http://www.american-rails.com/20th-century-limited.html They wrote up a much better description of the Twentieth Century Limited than I ever could.
"The New York to Chicago corridor was one of the most hotly contested passenger markets east of the Mississippi and New York Central’s 20th Century Limited competed with Pennsylvania Railroad's Broadway Limited for top honors, a rivalry which persisted for decades (based from historic traffic figures the Century did have a slight edge over the Broadway). Few trains have carried the aura of Central's original streamlined version of the Limited, which featured perhaps the greatest example of shrouding ever applied to a steam locomotive. As flag bearer of the "Great Steel Fleet" the Limited's service was second-to-none, matched only by the Broadway. As interest in rail travel waned after World War II and a merger with Pennsylvania looming by the late 1960s NYC chose to discontinue its once proud creation fearing service would slip unacceptable levels."
The summary on the back of the post card reads: "The Century is more than a train - more than a thing of steel and steam and electricity - more than an achievement of American engineering genius. Through thirty-three years of continuous service, the 20th CENTURY LIMITED has come to represent the spirit of American transpotation."