A search for "postcode district population" leads me to an FOI request which points me to table KS101EW in the Nomis census data.
I'm then about four clicks from this spreadsheet:
with 2011 census population. You didn't specify a population time point. This time next year you might get 2021 census population.
This is England and Wales only, so you'...
I will post and expand upon the answer provided by JonasV in his comment to the original post. If JonasV wants to post an answer, I would be happy to mark that as the answer. Based on his answer, here are two web sites with the data I was looking for:
TONY - https://anthonylouisdagostino.com/bounding-boxes-for-all-us-states/ - has 56 states and territories – ...
If you're looking for data, please try https://opendata.stackexchange.com/.
Two expressions in QGIS will give you exactly what you want:
( y_min( $geometry ) + y_max( $geometry ) ) / 2
( x_max( $geometry ) + x_min( $geometry ) ) / 2
If you're just looking for extreme values of x/y coordinates, you could use QGIS with this expression (e.g. in the field calculator): x_max( $geometry) - replace x with y and max with min for the according values.
Download a vector file for US states, e.g. from OpenStreetMap. There are different ways to do than, one is using Overpass Turbo.
Create a ...