Introducing the Landscape of the United States series

[Boyd]

Just in time for Independence Day! Explore the changing face of America during the past 40 years with nine new maps covering the whole country. They use historical land cover data and 3d terrain to create an effect similar to aerial photography. The resolution is pretty low (about 125 feet per pixel) so you won't see small details, but they do a good job of capturing regional changes over time.

This was sort of an unplanned "project of opportunity" for me. Two weeks ago I was looking at data from the National Land Cover Database (NLCD) and noticed they have recently re-processed their historical data for every year between 1985 and 2024. This seemed like a nice holiday-themed project, so I dropped everything and have just now finished (each map took about 22 hours just to render). More information about how these maps were made here, or just click the map info button in the app

Haven't spent a lot of time pouring over all these maps yet but have a few initial impressions. For starters, you can see a fair amount of development in South Jersey between 1985-2024, but most of it appears to have displaced agriculture and not forests. You can compare 1985 to 2024 here

https://boydsmaps.com/sync/#11/39.824632/-74.959226/nlcd1985/0/0/nlcd2024/11/0/0

But our poor little state is so heavily developed already, it doesn't looks as significant as I would have expected. The place that really surprised me is Atlanta, GA: that area has just exploded over the past 40 years. I guess it's good for the economy, but... wow.

https://boydsmaps.com/sync/#10/33.924012/-84.253660/nlcd1985/0/0/nlcd2024/10/0/0

Another example of suburban sprawl that surprised me is Boise, ID.

https://boydsmaps.com/sync/#11/43.608954/-116.456349/nlcd1985/0/0/nlcd2024/11/0/0

One that didn't suprise me is Las Vegas (notice how Lake Powell is shrinking too)

https://boydsmaps.com/sync/#11/36.169633/-115.144856/nlcd1985/0/0/nlcd2024/11/0/0

And it's also sad to see the receding waters at Salt Lake City

https://boydsmaps.com/sync/#9/41.123111/-112.532857/nlcd1985/0/0/nlcd2024/9/0/0

It's a big country and there's a lot more here for all of us to discover. Have not made a final decision yet, but will probably add more of these maps - maybe even all 40. Seems like this might be a good resource for people who want to find out which year the dam broke, when there was a forest fire, etc.

As usual, you may need to clear your broswer cache to see the new maps. This is covered towards the end of the help file.

Enjoy - and happy Fourth of July!

 

[bobpbx]

I recall reading several times about Atlanta and the beautiful trees and decent weather. I'll have to run through that area some time (yeah, sure bob, like you have many years left).

 

[Boyd]

Just added the 2016, 2017, 2018, 2019, 2021, 2022 and 2023 maps to this series, so we now have maps for every year from 2015 - 2024. Will continue working my way down the list until there's a map for every year, going all the way back to 1985.

I also have legacy (pre-LandSat) USGS landcover data which is cited as 1970-1985. Apparently, this is the old hand-drawn maps where they traced outlines on aerial photographs to show different landcover types. At some point during the late 1970's - early 80's they digitized all this which was a big project that took years, trying to correct problems, etc. I guess they just called it quits after they had the satellite data, so it isn't exactly clear what time period this legacy dataset represents. My assumption is that it's 70's based and they spent the later years just digitizing and cleaning it up, but we will have to wait until the map is done to try and figure that out. Anyway, it's very different in style from the Landsat-based maps, so it will be hard to make direct comparisons, but still worth including from a historical point of view (as the first USGS digital landcover database). I'll include this with the next upload in a few more days. If I can keep up the pace, the whole series will be done in late July.

 

[Boyd]

Five more maps are now available: 2011, 2012, 2013, 2014 and then there's 1975, which is an interesting one as I mentioned above. I suspect the date depends on exactly which part of the map you're looking at. But my sense is the same, this is 1970's data that was only re-formatted in the 1980's and 90's. Here are a couple local examples.

We can see the Commodore Barry Bridge and its approaches are still under construction in this map. That matches my 1970's aerials, where I think this particular part is from 1972. The bridge opened in 1974.

https://boydsmaps.com/sync/#12/39.814540/-75.357332/nlcd1975/0/0/pines1970/14/0/0

Another example is King's Grant, which is shown as a construction site on this map. On my 1970 aerials (I think this part is actually from 1970) it just looks like woods with no sign of construction. But the 1980's aerials show it about half finished.

https://boydsmaps.com/sync/#12/39.850922/-74.878053/nlcd1975/0/0/pines1970/12/0/0

There are other clues - it shows parts of Interstate 676 under construction, also Route 55. It also shows several failed developments as construction sites. These show up as roads that have been cleared on the 1970's aerials, but then they just gradually grow over and fade away in subsequent years. I chose a date of 1975 for this map, which is a bit arbitrary but it's in the right ballpark (I think). Bear in mind, all maps in this series are using ASTER terrain from 2009-2011, so you may see some "ghost" features in earlier maps.

This dataset only included some major interstate highways but no other roads, which made it look very "naked" when compared to the other maps. So, I set out to find some vintage roads to use. The oldest national dataset I could find was from 2012 and only included major roads without residential/local roads. Tried that but was not happy with the results. Then I remembered the old USGS Digital Line Graphics (DLG) topo maps. These were a companion to the DRG topo maps, but the first completely digital (vector-based) topo maps. But, just like the DRG maps which used to be easily found, I came up empty in my search for the DLG maps. All the links led in circles and ended up on this page. Damn... missed it by about three months!

USGS DLG's are no longer available thru EarthExplorer as of April 8, 2025.

Oh well, pretty sure these were from the 1980's and not 1970's anyway, but now I'll never know. In the end, I used the same roads from the 1985 NLCD map. In 2024, the USGS re-processed all these historical landcover maps and used additional data plus deep learning to enhance them - they did a really nice job IMO. One cool thing they did was make it possible to separate the roads from everything else, so that's what I used - 1985 roads. Would have liked 1970's roads better, but these are pretty close and they make the 1975 map much easier to compare with the newer maps in the series. Here's 1985 vs. 1975.

https://boydsmaps.com/sync/#10/39.741632/-74.725961/nlcd1985/0/0/nlcd1975/10/0/0

Anyway, this map is very different in style from the 1985-2024 Landsat-based maps. It shows large areas of landcover types without the detail of the satellite imagery. But still interesting for comparison as it clearly shows an earlier time when there was less development. Also worthy of inclusion as a tribute to the people who made the original maps "the hard way" back in the 70's.