What caused the different migrant families to "huddle together" in areas that provided shelter and water?

The migrant families huddled together in the hopes of staying dry, but most of all they huddled together for warmth.

"Awright, now, get off them clothes," Ma said. "I got some nice coffee for you fellas. An' you got dry overhalls to put on. Don' stan' there."

The evening came early. In the boxcars the families huddled together, listening to the pouring water on the roofs.