I created a database, trying to list all urban areas with at least 100,000 inhabitants.
I wanted to do this quiz series using urban areas to avoid obscure suburbs. However, I did not group international cities together, so e.g. El Paso and Juárez will remain separated despite their proximity.
The main source is OECD's worldcitiestool.
In case of omissions (e.g. Iquitos, Peru) or untrustworthy population figures (Comilla, Bangladesh having 8 million inhabitants), both populationdata.net and citypopulation.de have been used as secondary sources.
Last but not least, obvious suburbs have been grouped together.
It's strange not to find Atlanta on this list since its metro area (5.7 million) is the ninth largest in the US, but the population of the city proper is 472k.