I reposted the Craigslist ad for my neighbor who is selling firewood. I went into Craigslist to double check....and I could not find the ad!
Then I noticed that the default sort (in the upper, right corner) was set to "relevant". I switched it to "newest" and the ad showed up. Switched it back to "relevant" and it disappeared.
What a puzzler.
I finally got it to show up with the default "relevant" sort after adding "firewood" in the body of the ad in addition to the title. While I was at it I also added "fire wood" because the search in Craigslist looks for exact word strings.
I learn something new every day. The trick is to not forget one important thing every day.