"mom": How to transition from two columns back to one?

[Steve Ross]

Groff Mailing List,
I'm a new user of "groff" and "mom", so please let me know if this is not the 
appropriate forum for my question...
With version 2.4 of the "mom" macro package, and in its "document processing" 
mode (as opposed to the "typesetting mode"), I would like to put the majority 
of my document in two columns, but then exit back to one column before adding 
more text.  So, the last page would look something like this:
 __________________________________________________/|                           
                      ||                                                  || 
First column of text.    Second column of text.  || First column of text.    
Second column of text.  |
| First column of text.    Second column of text.  |
| First column of text.    Second column of text.  |
| First column of text.    Second column of text.  |
|                                                  || Another line of text 
which is now in one column  || rather than two.                                 
||                                                  |
|                                                  |
|__________________________________________________|

Is there a way in "mom" to force it to (more or less) evenly fill both columns 
with text and then exit back to a single column mode?
Thanks in advance for any direction,-- Steve Ross