Many of my old digital notes have a time and date and could be converted into a Zettelkasten Note, but they don't have a timezone. When importing these notes, I can use the following moment.js code to find the timezone of a date and time that is missing a UTC offset:

var moment = require("moment-timezone");
var zone = "America/Chicago";
var format = "YYYY-MM-DD-HHmmZZ";
document.write(moment.tz("2021-10-31 12:10", zone).format(format));

This code can be run quickly in a moment.js sandbox.

Source: momentjs.com