Tsarin ƙirar nuclei da yawa shi ne samfurin tattalin arziƙi wanda Chauncy Harris da Edward Ullman suka ƙirƙira a cikin labarin shekara ta 1945 "Yanayin Biranen". Samfurin ya bayyana shimfidar birni, bisa Chicago. Ya ce koda yake wata gari ta fara da gundumar kasuwanci ta tsakiya, ko CBD, wasu ƙananan CBDs suna haɓaka a bayan gari kusa da wuraren mahimman gidaje don ba da damar gajeriyar tafiye-tafiye daga wajen birnin. Wannan yana haifar da nodes ko cibiyoyi a wasu sassan birni banda CBD don haka suna ƙirar ƙirar nuclei da yawa. Manufarsu ita ce samar da mafi inganci, idan mafi rikitarwa, ƙirar. Babban burin su a wannan shine kamar haka: Motsawa daga ƙirar yanki Gara nuna yanayin rikitarwa na biranen, musamman waɗanda suka fi girma Samfurin yana ɗauka cewa: Ƙasa ba ta kwanciya a duk yankuna Akwai ma Rarraba Albarkatu Akwai ma Rarraba mutane a wuraren zama Akwai ma Kudin Sufuri Harris da Ullman sun yi jayayya cewa birane ba sa girma a kusa da tsakiya ɗaya, a maimakon haka da yawa daban. Kowane tsakiya yana aiki kamar wurin haɓaka.