Eminent domain, to take all the land that will be needed, is going to take a long, long time.
So tell me, what if your property is on the other side of the fence?
Build it in the center of the Rio Grande. Let em climb over that.
The middle of the river is not private land. The feds claims rights to all waterways in America, including the Rio Grande. Building a wall right down the middle won’t interfere with private property, animal watering, irrigation, et al. Where the border is on dry land, the government can take or lease an easement of 20ft along the border without needing to take the property itself.