When you are on your way to Azealea Town, a Pokemon center is on the route there. Go inside and talk to the fisherman and say yes and you'll get the old rod.
at olivine city
in golden rod city
its in migginiggins garage outside portrush
near lavender town's route
you will find it in a house somewhere
It is in golden rod city
explore a bridge in kanto
In the golden rod tunnel
the fishing guru gives it to you in olivine city
you do ecruteack city
if I remember right its in a house in Olivine City
in golden rod city!