Read a Sci-Fi short story as a kid. Can't remember or find the name of it.
Earth is overpopulated, everything is concrete and a search has begun for a new planet with natural resources intact for mankind to transition to.
Main character is a young girl who helps out her elderly neighbor some, and as the last ships are leaving Earth, she realizes that her neighbor is still back at home. She rushes there to find him digging a hole in the concrete, and she panics as the last ship leaves earth in a cloud of exhaust. She says they've missed their chance to go to "New Earth" and the old man responds "No we didn't. This is the new earth. They took the old one with them" as he plants a tree in the hole he's busted in the concrete.