I’m very curious about that too. They do what their organizers tell them.
I asked the same question here a few weeks back and was told that they knew they could get through to CA - while TX would have been a lot closer to the route they were taking, they knew they wouldn’t get across easily. Well, looks like that proved to be untrue. It only took a look at the map they were showing that they could easily have gone north and been at the border with TX a lot sooner. I think the trucks and buses and the help they had along the way had it planned out for CA!