I’ve started digging into Donald Pizer’s new annotated version of Manhattan Transfer and it’s awesome.
Here is a very helpful note on page 3 that explains the context of the title: “During this period, [1896 to 1904] rail passengers wishing to cross the Hudson River from New Jersey to Manhattan left the train at the Jersey shore and took a ferry across the river. Only when the Pennsylvania Railroad completed its construction of dual tunnels under the Hudson in 1910 was it possible for passengers to avoid the ferry by transferring from the steam trains of the New Jersey main line to the electric powered trains required for tunnel traffic. The New Jersey Manhattan Transfer rail station was built to accommodate this transfer.”