Block parent folder in robot.txt, but not children

[Zuken]

Example:

I want to block this URL (which shows up in Webmaster Tools as an error):

http://www.siteurl.com/news/events-calendar/usa

But not this:

http://www.siteurl.com/news/events-calendar/usa/event-name

[ABullis]

You could use "allow" in your robots.txt file for just this problem.

allow: news/events-calendar/usa/event-name

disallow: /news/events-calendar/usa

See the allow directive section of this page: https://en.wikipedia.org/wiki/Robots_exclusion_standard

[Martijn_Scheijbeler]

The idea from Andrew is nice, but my guess would be that you're targeting multiple events so that might run into issues. What you could do is add some more regular expression and make it like this:

Disallow: ^/news/events-calendar/usa$