How best to set up relationship between city - county tables?

[MLH]

There are some 800+ cities/towns/placenames in NC
and exactly 100 counties. I would like to have tblCities
and tblCounties set up so that a city whose geographic
boundaries extend say into 3 different counties can be
accurately represented.

I was thinking tblCities related one-to-many to tblCC (or
tblCityCounty) and then tblCC related many-to-one to
tblCounties. tblCC, of course, being a junction table
between tblCities and tblCounties. All cities, of course,
have a unique name - as do all counties.

Would you recommend natural keys here or should I
number cities and counties (say with autonumber) for
some reason?

[MLH]

And, one more thing...

The junction table (tblCC) would have an ID
field from both the cities and counties table.
Shoiuld I index the junction table on both of
these fields. We're not talking about many
records here, for one thing. And I don't think
I'll be sorting on any of the junction table's
fields either. So, would an index ANYWHERE
in the junction table serve no useful purpose?

[pietlinden]

Hopefully this doesn't come across as a smartass answer, but one way is
to use GetTickCount and time the two alternatives... then you can
decide for yourself.

[MLH]

Most certainly, it is a smart answer (dropping the "ass"). You see, I
hadn't even given any thought as to that being a primary consideration
but now that you mentioned it, I can see it could come into play. You
are suggesting, after I run the test, that if a time savings exists
between the two, that in itself is reason enough to go with the index.
Of course, the nature of the data is fairly static. No new counties
will be added. Maybe a city or two every decade - dunno. So not
much time will be wasted updating indices.

Hopefully this doesn't come across as a smartass answer, but one way is
to use GetTickCount and time the two alternatives... then you can
decide for yourself.