Maybe use a different geometry manager? grid perhaps? Just remember to not mix geometry managers in a single container widget. e.g. Below, the stuff in $mw is 'pack'ed but the stuff in $frmTop is 'grid'ed.

UPDATE: added -sticky attributes.

#!/usr/bin/perl

use strict;
use Tk;

my $btypes;
my $locations;
my $bstats;

my $mw;

$mw = MainWindow->new;
$mw->geometry("400x300");
$mw->title("First App");

my $frmTop = $mw->Frame(-bd => 2,-relief => 'ridge')->pack(-side => 't
+op', -fill => 'x', -pady => 3);

# Location label/entry
my $lblLocationsID = $frmTop->Label(-text => "Locations")
  ->grid(-row => 0, -column => 0, -sticky => 'w');
my $edtLocationsID = $frmTop->Entry(-textvariable => \$locations,-back
+ground => 'white')
  ->grid(-row => 0, -column => 1);

# type label/entry
my $lblBtypeID = $frmTop->Label(-text => "Types")
  ->grid(-row => 1, -column => 0, -sticky => 'w');
my $edtBtypeID = $frmTop->Entry(-textvariable => \$btypes, -background
+ => 'white')
  ->grid(-row => 1, -column => 1);
        
MainLoop;
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