The border between Mexico and the US is unique in the world as it separates two countries with the greatest economic disparities of any other international border. Building a wall is a convenient concept, which on the surface seems like a straightforward way to solve our illegal immigration problems by physically blocking immigrants.
But we already have walls erected in strategic locations along the border. And spending billions of dollars on a bigger, stronger wall is pointless when advanced technology like drones could effectively expand the existing wall at a much lower expense. Removing economic incentives to immigration, like sanctuary cities, and moving to a merit based system of immigration, will do far more to curb illegal immigration than a physical wall, at absolutely no cost whatsoever. Rather than building an expensive wall, I would prefer to see our precious federal tax dollars invested in more urgent needs such as maintaining critical infrastructure (for example roads, sewage, and water ways), feeding the hungry, housing the homeless, and protecting our environment.