When we say Mesa County is the 4th largest county in Colorado, it is to say that Mesa county is the 4th largest based on land area. How many square miles are within Mesa County? 3,328 to be exact according to USA.com.

Using land area as our ranker we can take a look at all 64 counties to truly determine which one is the largest and which is the smallest.

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Try to Guess Which Colorado County is the Largest

No peaking! Can you guess which one it is? I guessed Moffat County just because the horizon seems endless as you drive up to Dinosaur National Monument, but I was wrong. By about 1500 square miles. Continue to the photo gallery below to see them all, and to find out which county has the most square miles in Colorado.

Which Colorado County is the Smallest?

The county maps around the Denver metro have probably changed more often than any other place in the state. The county of Broomfield sits between Denver and Boulder and is Colorado's smallest county. Scroll on to find out how small. Broomfield is also Colorado's youngest county, established on November 15th, 2001.

The History of Colorado Counties

The story of the development of the state of Colorado county by county is pretty cool to look at. I'd love to make a timelapse video. In 1866, western Colorado was still part of the Colorado Territory and consisted of six counties. Grand Junction used to sit in Lake County which extended all the way to Utah.

We'll show you all 64 counties largest to smallest, and how each one got here in the photos below.

All 64 Colorado Counties Ranked By Size Smallest to Largest

We're ranking Colorado counties by land area to determine the largest to smallest of all 64 counties in the state. Find out about the land area of each county and how many people live there by scrolling through the photo gallery below to find out which ones are really the biggest.

KEEP GOING: See How Colorado's County Maps Evolved from 1850 to Today

See the amazing transformation that occurred on Colorado's county maps beginning in the 1860s and evolving into Centennial State we know today. Did you know that in 1866, Summit county went all the way to Utah? That same year, the area that would be known as Grand Junction was originally part of Lake County.

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