Here’s Rep. Henry Cuellar (D-Texas) during last week’s House-Senate Conference Committee meeting on the 2019 federal budget, which hinges on President Trump’s demand for a border wall. Cuellar is pointing to a map of the U.S.-Mexico border in his district.

“We have a river that doesn’t run straight,” he says, reminding his colleagues that past fencing built in the area has often had to get put up as much as a mile inland from the actual border. It’s impossible to build a sinuous fence following the contours of the river’s bank, right in the middle of an active floodplain.

Remember this map anytime someone tries to tell you that a border wall will stop Central Americans, or anyone else, from crossing onto U.S. soil to petition for asylum. In South Texas, there’s no way to keep people from rafting across and setting foot on U.S. soil, where they can await the arrival of Border Patrol agents and ask to apply for asylum. If you’re between the river and the wall, you’re still on U.S. soil, and no “metering” can steer you away.

“Congress has already funded 33 miles (53 kilometers) of new barrier construction here” in south Texas the AP’s Nomaan Merchant reported in late January. “But much of that new barrier will be built north of the Rio Grande, which carves a natural boundary between the U.S. and Mexico. That means migrants will still be able to reach American soil in front of the newly constructed barrier and request asylum.”

Nearly 60 percent of everyone whom Border Patrol is apprehending right now are children and families, most of them asking for protection. In Texas, a wall wouldn’t change that at all.