hi all i have a problem querying date

$from='2007-11-14';
$to='2007-11-16';
$query="select * from table where field_date between '$from' and '$to'";


it displays range from 2007-11-14 to 2007-11-15.?why is 2007-11-16 is not included?? how would i query then if i want to include 2006-11-16 without changing the value of my variables.