This is because XML::Simple by default cut the root node, since on XML we only have one root tag. Also you typed _CITY, upercase, that is different of _City, since XML is case sensitive. So, you actually should use:

  print $xml->{_City} ;
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If you use XML::Smart it has an option to load a XML and parse all the nodes and attributes in upercase or lowercase:

  use XML::Smart ;

  my $xml = XML::Smart->new(q`<USER _City="testboro"></USER>` , uperta
+g=>1 , uperarg=>1);

  print $xml->dump_tree_ok ;
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Output:

$VAR1 = {
          'USER' => {
                      '_CITY' => 'testboro'
                    }
        };
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