string to set timezone attribute of datetime. Default is an empty quote, which converts the
datetimes to UTC (properly accounting for daylight savings times based on the data's provided tz_cd column).
Possible values to provide are "America/New_York","America/Chicago", "America/Denver","America/Los_Angeles",
"America/Anchorage","America/Honolulu","America/Jamaica","America/Managua","America/Phoenix", and "America/Metlakatla"