First published as The Silver Locusts, this is a collection of short stories about a fleet of locust-like spaceships leaving Earth to settle Mars. In this world the Martian air is just about breathable but thin, and the first astronauts find abandoned city after city with water rippling through canals. They start to see ghosts and gradually we find that there are some living Martians, though perhaps they live only as memories.
But Earth is too crowded and people come to settle, bringing juke joints, small homes and beauty parlours - recreating small town America which was Bradbury's home. In one story, the war on Earth escalates and strangely most Mars settlers think they should return - not a great idea when war means nuclear war. A young man left alone decides to find a young woman if one is left, and rings every beauty parlour until he finds one. (This female would have been out securing food.) But his idea doesn't seem so great after a while and he leaves her, stumbling onto a couple of females who are actually androids built by a nutty professor, not that he knows that.
Other stories such as Billion Year Picnic at the end tell of a family exploring Mars looking for a city to settle in, knowing that now there is no going back to a devastated Earth and they have become the Martians for real.
One or two of Bradbury's stories were omitted from the collection, such as the tale of the ship full of coloured people who left homes in America for a better future, but most of them are more social comment than hard science, a warning that the future of humanity may depend on our ability to leave this planet and a query as to what we will bring and build.
Because this was never hard SF it has not dated, so read it as a fantasy or allegory and enjoy.