The most winter time is seen in the UTC time zone. You can get more information about time zones at the Wikipedia. Once on the page, type "Time Zone" into the search field at the top of the page and press enter to bring up the information.
Chicago is in neither. It is in the Central Time Zone.
Gainesville, Florida is in the Eastern Time Zone (ET). This time zone observes Eastern Standard Time (EST) during the winter months and Eastern Daylight Time (EDT) during daylight saving time in the summer.
Area code 801 is Salt Lake City, Utah, so it is in the Mountain Time Zone (MST in winter, MDT in summer).
Area code 715 is in Wisconsin, in the Central Time Zone (CST in winter, CDT in summer).
Area code 502 serves Louisville and Frankfort, Kentucky. It is in the Eastern Time Zone (EST in winter, EDT in summer).
Eastern in the summer and Central in the winter
No, Arizona is not in the Mountain Daylight Time (MDT) zone during winter. Most of the state observes Mountain Standard Time (MST) year-round and does not observe Daylight Saving Time, meaning it remains on MST during winter months. However, the Navajo Nation in northeastern Arizona does observe Daylight Saving Time, so it follows MDT in the summer.
...Eastern standard time
Area code 765 serves part of Indiana, including Lafayette and Muncie. It is in the Eastern Time Zone (EST in winter, EDT in summer).
In the US Eastern time zone, it started on December 21, some time after 11 pm.
No, Colorado is entirely in the US Mountain Time Zone.
Area code 859 primarily serves Covington through Lexington, KY. It is in the Eastern Standard Time Zone (EST in winter, EDT in summer).