use IO::Uncompress::Unzip;

my $sn=$fips2state->{$sfips}.'2010.sf1'; 
my $zf=$dir0.'/sf1/'.$sn.'.zip';
my $mf=$fips2state->{$fips}.'geo2010.sf1'; ;

my $member = IO::Uncompress::Unzip($zf, Name => $mf);
while (<$member>)
{
    #... pull out datums AREALAND AREAWATR POP100, create density 

}
close $member;