---
title: Day 27 – Boundaries – 14 States Split by Different Timezones! 
permalink: day-27-boundaries-timezone-boundaries-in-the-contiguous-us
date: 2025-11-27T21:28:12-05:00
tags:
  - 30DayMapChallenge
  - Python
  - DataViz
  - Maps
---

### Day 27 – Boundaries
**[Challenge Description](https://30daymapchallenge.com/#:~:text=Map%20lines%20of%20division%E2%80%94political%2C%20physical%2C%20ecological%2C%20or%20conceptual.%20Explore%20the%20meaning%20and%20impact%20of%20a%20dividing%20line%2C%20real%20or%20perceived.):** 	Map lines of division—political, physical, ecological, or conceptual. Explore the meaning and impact of a dividing line, real or perceived.


### My Submission

You might know the US has multiple timezones—to be exact, 4 timezones (Eastern, Central, Mountain, Pacific) in the contiguous states. But did you know that individual states can span different timezones? Since the US is a federal country where many policies are state-based and vary by state, I assumed each state would have a single timezone.

However, by mapping the timezone boundaries, we can see that **14** states are actually split across 2 different timezones!


![Timezone Boundaries in the Contiguous United States: 14 States Split by 2 or More Timezones](../assets/Timezone%20Boundaries%20in%20the%20Contiguous%20United%20States.png)

[Click here to view high-quality PDF ⬆️](../assets/Timezone%20Boundaries%20in%20the%20Contiguous%20United%20States.pdf)

### Further Ideas

These states end up in two different time zones simply because the federal government tries to match time zones to **where people actually live and work** — so the dividing lines follow **economic ties, commuting patterns, and local preferences** rather than clean state boundaries.

For example, most of Indiana is on Eastern Time, but the counties near **Chicago** use Central Time because daily life there, commutes, business hours, and media—are all tied to Chicago, not the rest of the state.

What I want to do **later** is look at what’s happening around these boundaries, like mapping income levels on each side to see if the timezone split also reflects differences in communities.


### References  
- Source Data: 
  - US County Data – [US Census Bureau](https://www2.census.gov/geo/tiger/TIGER2023/COUNTY/)
  - Timezones – [Timezone Boundary Builder](https://github.com/evansiroky/timezone-boundary-builder)
  - [Wikipedia: Time in the United States](https://en.wikipedia.org/wiki/Time_in_the_United_States)


*Made by [Matt Zhu](https://mattzhu.net) for the [#30DayMapChallenge](https://30daymapchallenge.com/).*