Only been in one taxi my whole life, and that was in Cozumel, Mexico, and you'd think that with my travels that have taken me to 6 continents, would have "forced" me to take a cab, but we always have a car, How much are a cab fares/ per mile.

Every city has its own rate. As you didn't specify a place, hard to know the correct answer.

Typically there is a flat charge (drop) when you enter the cab and after that the charge is based on distance (combined with waiting time if you're stuck in traffic). And yes, all of these rates are different for every location.

In Washington, DC, fares are based on zones. Conveniently, there is a zone around Union Station, and another zone around it . And zones when you change states to Maryland or Virginia.

In NYC when you get in a taxi there is an immediate charge of $2. FRom that point on the cost is 30 cents per 1/5 of a mile ( $1.50 a mile). There are reports the fare will go up in the near future.

This seems odd, but I've done it before: Call information for the city to which you're traveling and ask for the number to a cab company. Call the cab company and ask them how much it costs to get from the airport to your hotel (or which ever location you need to get to/from.) Granted, it's an estimate, but it'll give you an idea. I've used this method to do cost/benefit analysis on taking cabs vs. getting a rental car. If you're not going too many places during a long stay, the cab may be cheaper in the long run.