Colón is a port city on the northern shore of Panama that was founded in the 1850s as the Atlantic terminus of the original Panama railway; it was originally named Aspinwall, after one of the railway's builders.
The railway was a key transportation link for travellers on the Europe to Pacific
Coast route.1
For example, this 1858 despatch to Lytton announces that a Line of Screw Steamers from England to Vancouvers Island (via the Isthmus of Panama) will be forthcoming, adding that the first Screw Steamer will be despatched from England for Aspinwall with Passengers
on or about the first week in August.