Interplanetary Superhighway
https://www.nasa.gov/images/content/...ighway_med.jpg
This NASA illustration is conceptual, the real solution would require eating a spice that makes you eyes turn blue. (Frank Herbert reference). But the constrictions at each planet are Lagrange points.
This makes Lagrange point natural targets for asteroid recovery, rather than sending them to Earth orbit. Better to send up extraction and fabrication robots instead of finished goods.