The technology today are hundreds of times better than the steam shoves of that time period. But as far as where it should be built right here.

The United States should do this, from Texas to California along the boarder It would create jobs, with the additional benefits being, we can use the dirt to bolster eroding reef islands, eliminate the need for a fence along the boarder, and have revenue from the freighters, If we build it deep enough and wide enough for multiple super freighters to safely navigate the canal, the weight of the water would make it very costly and need major engineering to dig illegal tunnels under the canal to smuggle drugs and illegal immigrants across the boarder. Also from the toll fees we could build security outposts to monitor the shipping lanes, as well as add US Coast Guard presence. which would mean more jobs. Also if we build it so that both sides are on us soil we would not have to share the revenues. Also after the canal pays for it self the government can have another source of revenue to do more public works like a cross country high speed rail. As far as the environmental impact as far as I know there are no 3 headed calves being born from the results of the Panama Canal.