Yes, I support it.
I primarily support it on the southern border. Over 80% of our illegal immigrants hail from lands south of our border, not north. The countries in economic problems to the point that many of their citizens try to illegally immigrate are to the south, not to the north. You spend a good bit of savings to fix a toilet that's flooding your house and causing massive damage to the structure. You don't spend a good bit of savings to fix an occasionally drippy faucet that adds $.79 to your monthly water bill.
You begin it in conjunction with heavier enforcement of immigration laws and deportations, and once its part way through you start dealing with the notion of reformed immigration laws and what to do with those inside our country.
I would be fully in favor of figuring out a plan to allow illegals without other crimes to come forward and admit their illegality, go on a seeming "probation" type status, and work on the wall for a reduced salary and amnesty for their crime and potentially for IMMEDIATELY Family. I'd be in favored of forced labor working on the wall for those that are CAUGHT here illegally, with them serving their sentence doing hard labor building it. (I have a more detailed plan on this elsewhere).
I would be in favor of likely a two wall solution, with space in between and slanted at the top of each to make climbing the direction to the U.S. more difficult.
I don't think a wall is THE answer, or the only answer, but I do think it would help.