See help on conditional formatting.

gls858

You can use "Conditional Formatting".

You should start off by creating a data list of your cities in an
out-of-the-way area of your WS, say X1 to Z4.
X1 to X4 should be one class, and Y1:Y4 and Z1:Z4 the others.

Say you wish to format A1 to A20.
Select A1 to A20, with the focus of the selection in A1 (colored white).

Then, while all the cells are *still* selected,
<Format> <Conditional Format>
Change "CellValueIs" to "Formula Is",
And enter this formula in the second box:
=OR(A1=$X$1,A1=$X$2,A1=$X$3,A1=$X$4)

Then click on <Format>, and choose your format.
Then <OK>

Now, click <Add> to enter your second condition,
Again change "CellValueIs" to "Formula Is",
And enter this formula in the second box:
=OR(A1=$Y$1,A1=$Y$2,A1=$Y$3,A1=$Y$4)
Then click on <Format>, and choose your second format.
Then <OK>

Repeat for the third and final condition with:
=OR(A1=$Z$1,A1=$Z$2,A1=$Z$3,A1=$Z$4)
Set your 3rd format, then <OK> <OK>.

You now have to make sure that your entries into Column A are *exactly* the
same as you entered them into your data list.