I had to look that one up in the rules for use of Craigslist. Here is what it states:
Can I post my ad on more than one craigslist site?
Please choose just ONE craigslist site for which your ad is most relevant - this should generally be the site closest to where you are located. If your ad is equally relevant to all locations, your ad does not belong on local craigslist sites at all, please find another service.
Posting the same ad to multiple locations is considered spamming, and is prohibited.
How often can I post?
You may post to one category and in one city, no more often than about every 48 hours.
If you are submitting a post that is similar to another currently active post of yours on the site, you will get a blocked message. Removing the active post will allow you to post the new ad, unless the active post is less than 48 hours old.