Not with flights and container ships in a huge country like ours. They are smuggled in from Asia and the ME every day here in the ports of Florida.
Israel is a lot smaller than we are, and even there it only works because the law is enforced. Start enforcing it here.
Just because there are other illicit ways to get into the USA doesn’t mean the wall isn’t necessary or not going to work. It is non political means of security and cannot be undone by the next liberal idiot president. At a cost of a mere $20B over 4 or five years it is next to nothing in cost.