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This is my first experience with US cartography. I downloaded the US states from here https://www.census.gov/geographies/mapping-files/time-series/geo/carto-boundary-file.html (the layer is cb_2018_us_state_5m.zip [1.0 MB])

My default CRS in QGIS is EPSG:4326. After opening QGIS and adding the OSM base map, I insert such layer and I choose the first default transformation (NAD83 to WGS 84).

What can I do in order to visualize differently Alaska?

It is too big!

US

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  • 3
    There is no single right CRS for the USA, it depends on your desired usage. CRS codes don't need to be defined by EPSG either (other authorities exist)
    – nmtoken
    Apr 14, 2023 at 14:09
  • 2
    That looks like Web Mercator, which is, well, awful. The USGS has both CONUS and CONUS+AK/HI standard projections, though it's a huge area for a single map, and therefore quite tricky to get right.
    – Vince
    Apr 14, 2023 at 14:25
  • See MAPS OF HEMISPHERES AND CONTINENTS section in radicalcartography.net/?projectionref.
    – TomazicM
    Apr 14, 2023 at 14:49
  • Do you mean that you are happy with the contiguous states, but want to make Alaska, by itself, smaller? I don't think that's a great technique from a cartographic point of view, even if it is possible. As others have said, find a better coordinate system. Move Alaska into an inset area, if necessary, but don't resize it just to look good. Apr 14, 2023 at 18:22
  • Yes, a solution can be use a different CS for Alaska like this figure: mapsofindia.com/world-map/usa. But, how big should be Alaska in comparison with other states? Approximately, to which state is similar in terms of surface?
    – Geo_it
    Apr 15, 2023 at 7:08

3 Answers 3

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There is no "right" projection for anywhere.

That said, there are "standard" map projection formulations, originally defined by the European Petroleum Survey Group (EPSG), but now managed by a standards committee.

The projection you're calling a plate carrée of decimal degrees (WGS84), isn't, it's a Mercator, probably Web Mercator (EPSG:3857) like shown here, with the original screenshot at 1:50M scale (in ArcGIS Pro): enter image description here (Note that "scale" doesn't mean much in Mercator, because the poles are infinitely far from the Equator, but it does have Cartesian coordinates.)

This is a plate carrée of WGS84 decimal degrees (EPSG:4326, at the same scale): enter image description here (Note the long, straight border with Canada at the 49th parallel -- this indicates it's a cylindrical projection.)

And this is Albers Equal Area for North America, ESRI:102008 (again at 1:50M): enter image description here (The long USA-CAN border is now draped across a curve, showing that this is a conic projection.)

And this is the USGS Contiguous US Albers Equal Area, EPSG:5070 (original at 1:50M):

enter image description here (because its standard parallels are closer together and further south, Alaska is a bit wider as it curls away.)

If you want to retain Alaska and Hawaii in your map without using insets, and capture their relative size somewhat accurately, then you probably want to look for a Albers Equal Area for North America.

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In addition to the previous responses, I'll add the following, since you specifically mention Alaska. EPSG:3338 is commonly used for Alaska cartography and analysis, as shown here. enter image description here

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The cb_2018_us_state_5m.prj file show us that the native projection of the data is:

GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137,298.257222101]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]]

Running ogrinfo on the cb_2018_us_state_5m shapefile (ogrinfo -so c:\...\cb_2018_us_state_5m.shp cb_2018_us_state_5m) tells that this CRS is the equivalent EPSG:4269

Layer SRS WKT:
GEOGCRS["NAD83",
    DATUM["North American Datum 1983",
        ELLIPSOID["GRS 1980",6378137,298.257222101,
            LENGTHUNIT["metre",1]]],
    PRIMEM["Greenwich",0,
        ANGLEUNIT["degree",0.0174532925199433]],
    CS[ellipsoidal,2],
        AXIS["latitude",north,
            ORDER[1],
            ANGLEUNIT["degree",0.0174532925199433]],
        AXIS["longitude",east,
            ORDER[2],
            ANGLEUNIT["degree",0.0174532925199433]],
    ID["EPSG",4269]]
Data axis to CRS axis mapping: 2,1

You don't have to use the default QGIS CRS, but could instead set it to EPSG:4269. You can have QGIS reproject the OpenStreetMap xyz service to that CRS, then you get:

view of data in qgis in epsg:4269 CRS

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