especial sort

Hello,
My final dta file is of the following default format (sorted alphabetically by Metro Name).

Metro Name Variable1 Variable2
Metro1 ..... ....
Metro2 ..... ....
Metro3 .... ....
Metro4_Nation .... ...
Metro5 ... ...
Metro6 ... ....

I need to do a special sort whereby Metro4_Nation is moved to the top
(before Metro1) and rest of the Metros are kept in the same order. Any way to do this? Looks like "sort" or
"gsort" won't work here.

Thanks,
Umair