Old Python versions have reached end of life. It's about time to drop support for them.
This site shows the top 360 most-downloaded packages on PyPI (source) showing which have dropped support for a Python version.
Packages that are backports (for example, enum34) or known to be deprecated are not included (for example, distribute). If your package is incorrectly listed, please create a ticket.
See them all.
This is not an official website, just a nice visual way to measure progress. To see the authoritative guide on wheels and other aspects of python packaging, see the Python Packaging User Guide.
Fantastic, a problem found is a problem fixed. Please create a ticket!
You can also submit a pull request.
Thanks to Python Wheels and Python 3 Wall of Superpowers for the concept and making their code open source.