It's because wget defaults to only doing recursive download within the hostname that you used when you started.
http://ccachicago.org issues a redirect to http://www.ccachicago.org. Since all further links are under
www.ccachicago.org, wget will consider those links as being off-site and won't follow them.
The easiest solution here is of course to start with
wget -r http://www.ccachicago.org.
You could also add www.ccachicago.org to the list of domains to follow:
wget -r -D www.ccachicago.org http://ccachicago.org
For the future, you can find this kind of information by adding the debug flag. When I did that, I got
Deciding whether to enqueue "http://www.ccachicago.org/".
This is not the same hostname as the parent's (www.ccachicago.org and ccachicago.org).
Decided NOT to load it.
Redirection "http://www.ccachicago.org/" failed the test.