Then the train came
… As I write this at midnight now she’s somewhere near Omaha. (Windblown World, p.202)
He’s talking about his mum who, at that time (July 1949), left Denver again where Kerouac had bought a house for the whole family – his mum didn’t like Denver, so she left for New York with him following later on. He wrote about her leaving on the ‘Rock Island’, so she was probably travelling on the Rocky Mountain Rocket, not the California Zephyr (train No.5) that nowadays travels between Denver and Omaha. The photograph is taken inside Denver Union Station.