OnTimeZone.com provides borders for North American Time Zones including the United States, Canada, Mexico and points south. The data is designed for travelers, provided as images and as data files suitable for use in most routing or GPS software as well as Google Earth and Google Maps. We cover everything from Panama to the northern edge of the continent, and try to include all of the local exceptions to time zone observance, including Daylight Saving time rules.

Truthfully, there are two kinds of time zone maps. Those that are wrong, and those that are about to be wrong. We strive to be the latter.

Change is constant because communities near a current time zone border sometimes clamor for change, creating a political breeze which occasionally moves the ship of state - and a time zone border changes. In the US changes were made as recently as November 2010.

Ours is really just an "interpretation" of time zone data, because current time zone boundary data is elusive. And once you think you have nailed down the official "legislated" time zone, you learn about differences between that and the locally "observed" time zone (more on that in our "exceptions" page).

At OnTimeZone.com our goal is to make the lines reflect what a traveler is actually likely to encounter.

We intend to keep the data current as we move forward. In our change log you will see that we keep very current with any changes to North American time zone borders and observance.

The borders presented here includes recent changes in Indiana, North Dakota and Nayarit Mexico. All official changes through mid 2011 are included. There are likely errors -- converting information like this official description into accurate lat/lon based data is enough to give anyone a headache:

From the junction of the west line of Tripp County, South Dakota with the South Dakota-Nebraska boundary west along that boundary to the west line of R. 30 W.; thence south along the range line between Rs. 30 and 31 W. to the southwest corner of sec. 19, T. 33 N., R. 30 W.; thence easterly along section lines to the northeast corner of sec. 29, T. 33 N., R. 30 W.; thence southerly along section lines with their offsets to the northeast corner of sec. 17, T. 32 N., R. 30 W.; thence westerly along section lines to the northwest corner of sec. 18, T. 32 N., R. 30 W.; thence southerly along the range line to the southwest corner of T. 31 N., R. 30 W.; thence easterly along the township line to the northeast corner of T. 30 N., R. 30 W.; thence southerly along the range line to the southwest corner of T. 29 N., R. 29 W.; thence westerly along the township line to the northwest corner of sec. 4, T. 28 N., R. 30 W.; thence southerly along section lines to the southwest corner of sec. 33, T. 28 N., R. 30 W.; thence easterly along the township line to the northeast corner of sec. 4, T. 27 N., R. 30 W.; thence southerly along section lines to the southwest corner of sec. 22, T. 26 N., R. 30 W.; thence easterly along section lines to the southeast corner of sec. 24, T. 26 N., R. 30 W.; thence ... thence... thence...

Then there's Daylight Saving Time.

While most of the North America observes DST, there are significant exceptions. Such as the Canadian province of Saskatchewan, Arizona (except for the Navajo reservation), Hawaii, the Mexican state of Sonora, parts of eastern Quebec, and several smaller entities. Details in the "exceptions" page.

Just like "observed" time zones, someDST observation exceptions are officially sanctioned, some are merely local practice. So be warned.

Hopefully this all helps get you to dinner on time.