The population of a city is shaped by a small number of measurable forces: births, deaths, and migration, which can be modelled forward in time to reveal a community’s demographic future. Basel-Stadt displays a population structure typical of Swiss cities, with an above-average share of young adults drawn by its universities and employers, and has for decades combined a positive international migration balance with a persistent net loss of residents to other cantons. The most consequential finding from the data is that the canton’s natural population change – the balance of births and deaths – has turned negative, meaning deaths now regularly outnumber births, a shift that places even greater weight on migration to sustain growth.

At the end of 2023, the total population of Basel-Stadt stood at 206’308, with foreign nationals accounting for 37.0 percent of residents. Over the last five years, births to Swiss mothers have consistently exceeded those to foreign mothers, with 1’197 Swiss newborns compared to 640 foreign newborns in 2025. The overall number of births has declined from 2’074 in 2021 to 1’837 in 2025, a drop of roughly 11 percent. Deaths have fluctuated but remained above 1’800 each year, and in 2025 the canton recorded a birth surplus of just 36, meaning births barely exceeded deaths – a stark contrast to the death surplus of 377 seen in 2022. Migration data reveals a clear split: international migration has been strongly positive, with net gains of over 1’800 foreign residents in 2025, while intercantonal migration among Swiss nationals has been negative every year, with a net loss of 225 Swiss residents in 2025. The fertility rate in Basel-Stadt has fallen from 1.3 in 2020 to 1.1 in 2024, well below the replacement level of 2.1. Given the persistent death surplus and low fertility, the most relevant preset scenario to test in the simulator is the shrinking city scenario (Figure 5).

Figure 5 allows for generating different demographic scenarios and visualizing the population evolution over time. The simulation is a strongly simplified model: it projects births, deaths, and migration forward mechanically but omits real-world constraints that actually drive those same forces, above all the availability of housing, labor market conditions, and planned area developments within the canton. The Statistical Office of the Canton of Basel-Stadt published a detailed scenario analysis in 2023 that incorporates these factors and maps three development paths – high, medium, and low – through to 2045. Under the medium scenario, the population is projected to grow from 204’550 at end-2022 to over 224’000 by 2045, a level last seen in the mid-1970s. Readers seeking a full analysis are referred to the official report: population-scenarios.