What is the correct preposition to use following "average"? "The average cost of a meal across/among/over cities."

I want to write about "averages" and I need to indicate the dimension that those averages are calculated by.

Example: Let's say, I've visited multiple restaurants in multiple cities. When I say "The average cost of a meal ...", I might need to talk about ...

• The cost of a meal in different restaurants in the same city.
• The cost of a meal in restaurants of the same restaurant chain in different cities.
• The overall average cost of a meal.

What is the correct preposition to use here?

The average cost of a meal across?/among?/over? cities.

P.S. I've found this question on StackExchange which recommends the use of "of" over alternatives but that doesn't work for me here. I am using "of" but I need to indicate the overall group.

average across vs average among vs. average over

Solution 1:

I'm sure that different people will favor different alternatives, but of the three you've offered ("across", "among", and "over"), I prefer "over".

However, I'd probably let the object of the preposition dictate which preposition to use. For example:

The average cost of a meal in the five cities chosen . . . (since one eats "in" a city)

The average cost of a meal at the five Olive Gardens chosen . . . (since one eats "at" a restaurant)

The average cost of a meal between the hours of 6:00 pm and 8:00 pm . . . (since one eats "between" two times)

The average cost of a meal for people who can claim discounts . . . (since a meal has a cost "for" people)

It is to a great extent a matter of preference, though.