I don't think we will ever be able to relieve the pressure of over-population by sending the overflow into the solar system (let alone to the stars) - going to Mars & elsewhere and establishing bases or even colonies.. that is more about discovery & learning new science.
As for the teeming multitudes on earth.. that is easily within our control to stabilize. But, that is a hornets nest of controversy.. mainly due to ignorance & religion. Too bad. Life is about quality.. not quantity.
Meanwhile, visit here:
The Mars Society — The Mars Society
That and more here:
https://home.comcast.net/~davejanelle/ceres.html
Even Ceres has 4 million sq mi of surface to explore.