Ticket to ride, 1910: What are the big cities

Question

Earlier today I bought the 1910 expansion in the mobile version of Ticket to Ride. In the big cities variant, there's an achievement called "Urban Traveller", described by "Win while connecting all 7 Big Cities", but I haven't found an easily accessible list of what those are, so that's my question.

Answer 1

From the rules pdf (also quoted in this blog post) :

The Big Cities are Chicago, Dallas, Houston, Los Angeles, Miami, New York and Seattle.