where is the time zone change from eastern to central
Eastern Time Zone The boundary between time zones is set forth in the Code of Federal Regulations, with the boundary between the Eastern and Central Time Zones being specifically detailed at 49 CFR 71.[6]
Coordinated Universal Time The time zone using UTC is sometimes denoted UTC±00:00 or by the letter Z—a reference to the equivalent nautical time zone (GMT), which has been denoted by a Z since about 1950. Time zones were identified by successive letters of the alphabet and the Greenwich time zone was marked by a Z as it was the point of origin. The letter also refers to the "zone description" of zero hours, which has been used since 1920 (see time zone history). Since the NATO phonetic alphabet word for Z is "Zulu", UTC is sometimes known as "Zulu time". This is especially true in aviation, where "Zulu" is the universal standard.[24] This ensures all pilots regardless of location are using the same 24-hour clock, thus avoiding confusion when flying between time zones.[25] See the list of military time zones for letters used in addition to Z in qualifying time zones other than Greenwich.