A monorail wall with a mall.

A proposal from the National Consulting Service (NCS) calls for a wall with a monorail, which would travel along the 1,900-mile-long border, and a mall.

The National City, California-based firm said the transit system would help revitalize cities on both sides of the border, because the US and Mexico would share profits from transportation fares, according to the LA Times.

"The NCS Team believes the basis of our wall design concept to be a win-win for all; from US National Security, infrastructure, expanded commerce, transport, energy and cost savings efficiencies, and a the US-Mexico build partnership," the proposal's technical summary reads.