Spatiotemporal dynamics of informal settlements across argentine cities: A national-scale analysis

Informal settlements are expanding worldwide, yet global SDG 11.1.1 monitoring remains disproportionately focused on large metropolitan areas. This leaves a critical blind spot: the rapid growth of informal settlements in smaller urban areas. Using national-scale ReNaBaP data (2016–2023), this study quantifies, for the first time, the spatiotemporal dynamics of informal settlement growth across all Argentine cities above 2000 inhabitants. The analysis reveals that informal settlements are growing at an average annual rate of 1.79%. Contrary to prevailing assumptions, the largest total informal settlement area is found in extra-small urban areas (2000–50,000 residents; 267 km 2 ), exceeding even Greater Buenos Aires (216 km 2 ) despite its far larger population share. Between 2016 and 2023, the informal settlement areas in smaller urban areas expanded faster on average, i.e., small cities (50,000–200,000 residents) grew at 2.78% annually, compared with 1.44% in large metropolitan areas, and experienced sharper growth peaks (up to 5.06% in 2018). These findings reveal an emerging spatial shift in informal urbanization, where smaller cities, often absent from global datasets, are now critical frontiers of housing informality. Addressing this monitoring gap is essential for adequate housing, equitable resource allocation, and inclusive urban policy, both in Argentina and globally.