In column A are the names of the cities. In column B are the dates of all of
the events for that city. Here's what I would like to do:

In column C put the earliest date for the unique city
In column D put the latest date for the unique city

So if in column A, Houston is listed 5 times with date ranges from 1/1/2007,
2/1/2007, 3/1/2007, 4/1/2007 and 5/1/2007. In column C, I want 1/1/2007 and
in column D I want 5/1/2007.

There will be multiple cities, so then if there is another city Los Angeles,
then the earliest and latest date should be shown for that also.

Thanks in advance.