To attain a population for a district, Geography is pre-eminent. County lines, municipal boundaries and compactness are supposed to be the guiding lines.

A state that has 1 million people should get 2 congressional seats. If it votes 60% or 600,000 votes for one party, that party in theory should get both seats. However, if most of the majority party live in the one major city, which constitutes one of the two seats, then the state will send one representative  from each party.

No matter what you do, you cannot draw that state in such a way that you do no "pack" the urban voters together. A "pie" split of the city will not satisfy the compactness requirement, or the municipal/county line requirement.

Besides many urban districts are "gerrymandered" to ensure that Hispanic, or Black votes are not diluted. Chicago has several districts like that, and the Democrats were behind it.