What is the diameter of a telephone pole?

Telephone Poles, at least the old wooden ones, come in three sizes... 30ft, 60ft, and 90ft.

When one is installed, 1/3 of it is buried into the ground, so that means that the part above ground would be 20ft, 40ft, and 60ft high.

(This is for the United States, only.)

The newer Cement and/or Steel ones are more customizable.