{"slug":"cities","title":"Cities","definition":"Studies of urban form, financial centres, and infrastructure when population or African city growth changes.","connected_topics":[{"slug":"housing","title":"Housing","href":"https://greyscienx.com/topics/housing"},{"slug":"african-economy","title":"African economy","href":"https://greyscienx.com/topics/african-economy"},{"slug":"population-decline","title":"Population decline","href":"https://greyscienx.com/topics/population-decline"}],"study_count":3,"studies":[{"id":"GSX:POP-009","slug":"how-to-shrink-a-country-without-breaking-it","title":"How to Shrink a Country Without Breaking It","primary_question":"What happens to housing, cities, and public infrastructure under population contraction?","summary":"Housing, cities and public infrastructure under population contraction.","research_type":"exploratory_simulation","evidence_status":"modelled","series_slug":"population-futures","series_title":"Population Futures","version":"1.0","date_modified":"2026-09-28","links":{"html":"https://greyscienx.com/research/population-futures/how-to-shrink-a-country-without-breaking-it","markdown":"https://greyscienx.com/research/population-futures/how-to-shrink-a-country-without-breaking-it/markdown","manuscript":"https://greyscienx.com/api/v1/research/how-to-shrink-a-country-without-breaking-it/manuscript","json":"https://greyscienx.com/api/v1/research/how-to-shrink-a-country-without-breaking-it","pdf":"https://greyscienx.com/research/population-futures/how-to-shrink-a-country-without-breaking-it.pdf"}},{"id":"GSX:AFR-002","slug":"johannesburg-as-africas-financial-capital","title":"Johannesburg as Africa’s Financial Capital","primary_question":"Under what conditions could Johannesburg finance a continent-scale economy?","summary":"The conditions under which Johannesburg could finance a continent-scale economy.","research_type":"exploratory_simulation","evidence_status":"modelled","series_slug":"african-convergence","series_title":"African Convergence","version":"1.0","date_modified":"2026-09-28","links":{"html":"https://greyscienx.com/research/african-convergence/johannesburg-as-africas-financial-capital","markdown":"https://greyscienx.com/research/african-convergence/johannesburg-as-africas-financial-capital/markdown","manuscript":"https://greyscienx.com/api/v1/research/johannesburg-as-africas-financial-capital/manuscript","json":"https://greyscienx.com/api/v1/research/johannesburg-as-africas-financial-capital","pdf":"https://greyscienx.com/research/african-convergence/johannesburg-as-africas-financial-capital.pdf"}},{"id":"GSX:AFR-003","slug":"the-factory-for-african-urbanisation","title":"The Factory for African Urbanisation","primary_question":"How can South African production serve the infrastructure of African city growth?","summary":"South African production positioned around the infrastructure of African city growth.","research_type":"exploratory_simulation","evidence_status":"modelled","series_slug":"african-convergence","series_title":"African Convergence","version":"1.0","date_modified":"2026-09-28","links":{"html":"https://greyscienx.com/research/african-convergence/the-factory-for-african-urbanisation","markdown":"https://greyscienx.com/research/african-convergence/the-factory-for-african-urbanisation/markdown","manuscript":"https://greyscienx.com/api/v1/research/the-factory-for-african-urbanisation/manuscript","json":"https://greyscienx.com/api/v1/research/the-factory-for-african-urbanisation","pdf":"https://greyscienx.com/research/african-convergence/the-factory-for-african-urbanisation.pdf"}}],"related_questions":["What happens to house prices when population declines?","Can housing scarcity persist while population falls?","How should cities and infrastructure adjust when a country shrinks?","What would make Johannesburg Africa's financial capital?","How do continental growth and local institutions shape Johannesburg's financial role?","What industrial role does South Africa have in African urbanisation?","Which city-building goods could a South African factory system supply?"],"claims":[{"id":"GSX:POP-009:C01","claim":"In the central scenario, a 22.2 percent population decline by 2076 coincides with 3.5 percent more households. The same run can still produce a shortage of roughly 54,000 habitable homes after the city has lost 266,000 people.","study_id":"GSX:POP-009","study_title":"How to Shrink a Country Without Breaking It","href":"https://greyscienx.com/research/population-futures/how-to-shrink-a-country-without-breaking-it/claims/C01"},{"id":"GSX:AFR-002:C01","claim":"In the central regional-hub scenario, an 8 percent capture share produces about US$90.4 billion of cumulative financial-services revenue and about US$71.2 billion of value retained in South Africa.","study_id":"GSX:AFR-002","study_title":"Johannesburg as Africa’s Financial Capital","href":"https://greyscienx.com/research/african-convergence/johannesburg-as-africas-financial-capital/claims/C01"},{"id":"GSX:AFR-003:C01","claim":"In the central build-out, South African-linked firms record US$264 billion of cumulative gross sales and about US$137 billion of domestic value added over twenty-five years.","study_id":"GSX:AFR-003","study_title":"The Factory for African Urbanisation","href":"https://greyscienx.com/research/african-convergence/the-factory-for-african-urbanisation/claims/C01"}],"assumptions":[{"id":"GSX:AFR-002:A01","name":"Central hub shares","sensitivity":"high","study_id":"GSX:AFR-002","href":"https://greyscienx.com/research/african-convergence/johannesburg-as-africas-financial-capital"},{"id":"GSX:POP-009:A02","name":"Central shrinkage path","sensitivity":"high","study_id":"GSX:POP-009","href":"https://greyscienx.com/research/population-futures/how-to-shrink-a-country-without-breaking-it"},{"id":"GSX:AFR-003:A02","name":"Contestable share and retention","sensitivity":"high","study_id":"GSX:AFR-003","href":"https://greyscienx.com/research/african-convergence/the-factory-for-african-urbanisation"},{"id":"GSX:POP-009:A01","name":"Hypothetical Gauteng-scale city-region","sensitivity":"high","study_id":"GSX:POP-009","href":"https://greyscienx.com/research/population-futures/how-to-shrink-a-country-without-breaking-it"},{"id":"GSX:AFR-003:A01","name":"Urban anchor","sensitivity":"moderate","study_id":"GSX:AFR-003","href":"https://greyscienx.com/research/african-convergence/the-factory-for-african-urbanisation"},{"id":"GSX:AFR-002:A02","name":"Starting financial depth","sensitivity":"low","study_id":"GSX:AFR-002","href":"https://greyscienx.com/research/african-convergence/johannesburg-as-africas-financial-capital"}],"datasets":[{"id":"D01","title":"How to Shrink a Country Without Breaking It","study_id":"GSX:POP-009","href":"https://greyscienx.com/research/population-futures/how-to-shrink-a-country-without-breaking-it/data"},{"id":"D01","title":"Johannesburg as Africa’s Financial Capital","study_id":"GSX:AFR-002","href":"https://greyscienx.com/research/african-convergence/johannesburg-as-africas-financial-capital/data"},{"id":"D01","title":"The Factory for African Urbanisation","study_id":"GSX:AFR-003","href":"https://greyscienx.com/research/african-convergence/the-factory-for-african-urbanisation/data"}],"links":{"html":"https://greyscienx.com/topics/cities","json":"https://greyscienx.com/api/v1/topics/cities"}}