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3. NOAA Science Behind Marking the New U.S. Center of Population

**X Marks the Spot** The NOAA science behind the marking of the U.S. Census center of population  Aerial view of Hartville, MissouriHartville, Missouri, is the nation's "center of population," based on the latest U.S. Census data. NOAA scientists will mark this point with a commemorative bench mark in 2022. The center of population represents the average location of where people in the United States live. The United States has a new center of  population, and NOAA will mark the spot in the Ozark Mountains later this fall. We are inviting everyone to learn about the science behind this effort. This past fall, the Census Bureau announced  the 2020 U.S. Center of Population, which they  describe as a point where an imaginary, flat, weightless and rigid map of the  United States would balance perfectly if everyone were of identical weight.  This point represents the average location of where people in the United States  live. In 2020 the location was Hartville, Missouri, a town of less than 600  people. NOAA’s National Geodetic Survey will compute the exact longitude and  latitude of the commemorative mark of the  2020 center of population. The commemorative survey mark  is designed to be stable for many decades to come, if not centuries, and the  location will become part of the larger reference system. Surveyors rely on the  foundational positioning framework provided through geodesy, and their work is essential to modern commerce. When you see someone  at a construction site or the side of a road peering into complex optical  devices perched on top of a tripod, you are seeing someone surveying, and benefiting from geodesy. The precise  measurements they gather help us navigate the Earth (on the land, the sea, and  in the air) in an efficient, economical, and predictable way. It's challenging, though, because the Earth  isn’t a big ball, it is irregular and elliptical in shape. To make useful  measurements of this not-so-perfectly round spinning sphere, scientists have to  understand the way it curves, and all of the features across its surface, like  mountains and oceans. They also need to calculate the slight changes in its  gravity field over time and land movements. “When you try to measure the distance from one  place to another in a small area, you can mostly pretend it’s all made of flat  surfaces,” says Galen Scott from the National Geodetic Survey division of NOAA.  “But for larger distances, you have to account for the curvature of the Earth,  and that’s when it gets complicated.” In the past, geodesists assigned coordinates —  similar to unique address points — to various locations by using Earth-based  surveying tools to measure distances between locations. Now they use  space-based tools like the Global Positioning System (GPS). Consistency is key;  NOAA oversees the National Spatial Reference System, which is used throughout  the United States and territories and ensures that everyone is working from the  same coordinates. This fall the people of Hartville will  celebrate this new reference point by having a bit of a party to show off the  “center” of America. We will share  details when they become available. This is the fifth time in a row that the center of  population has fallen in Missouri. Movements were particularly large in years  when new states entered the union. NOAA and Census have partnered on this kind  of commemoration every ten years since 1960. Recording population movement and numbers can  help with distribution of congressional districts and planning for the  allocation of government resources and infrastructure needs over time.  Combining the count of people with long-distance measurements provides democracy  with important tools. “Geodesy is foundational to understanding  Earth,” Scott says.
 More **Information** U.S. Center of Population Based on 2020 Census Will Show if Southwesterly Migration Continued U.S. Census Bureau National Geodetic Survey   Get **Social** Social
 **Last updated:** 12/05/22 **Author:** NOAA How to cite this article Contact Us


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