|Letters and parcels must now be sorted.
Post Office workers must look at each letter.
They find out where each letter is to go.
They put the letters for each town or city into open boxes called pigeon holes.
Each pigeon hole is labelled to tell where the letters are to go.
When the men have sorted all the letters they take them out of the pigeon holes.
Then they tie together the letters for each town or City.
Air mail letters are tied in parcels by themselves.