Visualizing 200 Years of U.S. Population Density

At the moment, there are around 326 million people living in the United States, a country that’s 3.5 million square miles (9.8 million sq km) in land area.

But throughout the nation’s history, neither of these numbers have stayed constant.

Not only did the population boom as a result of births and immigrants, but the borders of the country kept changing as well – especially in the country’s early years as settlers moved westwards.

U.S. Population Density Over Time

From a big picture perspective, here is how population density has changed for the country as a whole over the last 200 years or so:

But today’s animated map, which comes to us from Vivid Maps, takes things a step further.

It plots U.S. population density numbers over the time period of 1790-2010 based on U.S. Census data and Jonathan Schroeder’s county-level decadal estimates for population. In essence, it gives a more precise view of who moved where and when over the course of the nation’s history.

Note: While U.S. Census data is granular and dates back to 1790, it comes with certain limitations. One obvious drawback, for example, is that such data is not able to properly account for Native American populations.

“Go West, Young Man”

As you might notice in the animation, there is one anomaly that appears in the late-1800s: the area around modern-day Oklahoma is colored in, but the state itself is an “empty gap” on the map.

The reason for this? The area was originally designated as Indian Territory – land reserved for the forced re-settlement of Native Americans. However, in 1889, the land was opened up to a massive land rush, and approximately 50,000 pioneers lined up to grab a piece of the two million acres (8,000 km²) opened for settlement.

While settlers flocking to Oklahoma is one specific event that ties into this animation, really the map shows the history of a much broader land rush in general: Manifest Destiny.

You can see pioneers landing in Louisiana in the early 1800s, the first settlements in California and Oregon, and the gradual filling up of the states in the middle of the country.

By the mid-20th century, the distribution of the population starts to resemble that of modern America.

Population Density Today

The average population density in the U.S. is now 92 people per square mile, although this changes dramatically based on where you are located:

If you are in Alaska, the state with the lowest population density, there is just one person per square mile – but if you’re in New York City there are 27,000 people per square mile, the highest of any major city in the country.

The World’s 25 Largest Lakes, Side by Side

In many parts of the world, you don’t have to look very far to find a lake.

According to satellite data, there are roughly 100 million lakes larger than one hectare (2.47 acres) to be found globally. The largest lakes, which rival the size of entire nations, are more of a rarity.

One might expect the world’s largest lakes to be very alike, but from depth to saline content, their properties can be quite different. As well, the ranking of the world’s largest lakes is far from static, as human activity can turn a massive body of water into a desert within a single generation.

Today’s graphic – created using the fantastic online tool, Slap It On A Map! – uses the Great Lakes region as a point of comparison for the largest 25 lakes, by area. This is particularly useful in comparing the scale of lakes that are located in disparate parts of the globe.

The Greatest Lakes

The largest lake in the world by a long shot is the Caspian Sea – a name that hints at a past when it was contiguous with the ocean around 11 million years ago. This massive saline lake, which is nearly the same size as Japan, borders five countries: Kazakhstan, Russia, Turkmenistan, Azerbaijan, and Iran. An estimated 48 billion barrels of oil lay beneath the surface of the basin.

The five Great Lakes, which run along the Canada–U.S. border, form one of the largest collections of fresh water on Earth. This interconnected series of lakes represents around 20% of the world’s fresh water and the region supports over 100 million people, roughly equal to one-third of the Canada–U.S. population.

Amazingly, a single lake holds as much fresh water as all the Great Lakes combined – Lake Baikal. This rift lake in Siberia has a maximum depth of 5,371ft (1,637m). For comparison, the largest of the Great Lakes (Lake Superior) is only 25% as deep, with a maximum depth of 1,333ft (406m). Lake Baikal is unique in a number of other ways too. It is the world’s oldest, coldest lake, and around 80% of its animal species are endemic (not found anywhere else).

Here’s a full run-down of the top 25 lakes by area:

Shrinking out of the rankings

Not far from the world’s largest lake, straddling the border between Kazakhstan and Uzbekistan, lay the sand dunes of the Aralkum Desert. In the not so distant past, this harsh environment was actually the bed of one of the largest lakes in the world – the Aral Sea.

For reasons both climatic and anthropogenic, the Aral Sea began receding in the 1960s. This dramatic change in surface area took the Aral Sea from the fourth largest lake on Earth to not even ranking in the top 50. Researchers note that the size of the lake has fluctuated a lot over history, but through the lens of modern history these recent changes happened rapidly, leaving local economies devastated and former shoreside towns landlocked.

Lake Chad, in Saharan Africa, and Lake Urmia, in Iran, both face similar challenges, shrinking dramatically in recent decades.

How we work to reverse damage and avoid ecosystem collapse in vulnerable lakes will have a big influence on how the top 25 list may look in future years.