*4.2. The Post-Crisis Effects on the Five Largest Spanish FUAs: Growing Variability within Urban Areas*

In this section, the paper analyzes how metropolitan dynamics have diversified inside FUAs by focusing on the five most populated ones in Spain. According to INE data, these are, in deceasing order, Madrid, Barcelona, Valencia, Seville, and Bilbao (Appendix A, Table A2). Concentrating first on differences between cores and peripheries (Figure 3), the five urban cores lost inhabitants during the economic crisis phase, notably so in Madrid. However, in the post-crisis phase, they began to recover their population figures once again. Seville is the only exception, as its population continued to decrease in the second period, though at a slower pace. Presently, Madrid is by far the most dynamic core, followed by Barcelona, Valencia, and Bilbao. More specifically, the cities of Madrid and Bilbao grew faster than their peripheries during the post-crisis phase, possibly indicating that they could be experiencing relative recentralization.

**Figure 3.** Core, ring, and the total FUA growth (for each of the five FUAs) in 2011–2015 and 2015–2019. Absolute numbers (**left graph**) and relative figures (**right graph**). Source: 2011, 2015, and 2019 Padrón Continuo (Continuous Population Register) microdata, INE.

> The suburban municipalities of the five FUAs all grew in both periods, Bilbao being the only exception, as their numbers slightly dwindled between 2011 and 2015. In general, suburban growth was higher in the post-crisis phase than in the preceding period, with the exception of Seville, whose periphery grew more during the economic crisis period. Therefore, these reducing suburbanization trends could indicate that the Seville FUA was recentralizing (in relative, not absolute, terms).

> Finally, as shown by the maps in Figure 4, the post-crisis economic recovery gave rise to a new metropolitan population growth phase, ending previous trends. During the economic crisis phase (2011–2015), the five FUAs analyzed were characterized by negative international migration and low suburbanization. Therefore, peripheries gained less population than in previous decades. Urban cores decreased due to both negative natural and migratory growth, though they stopped losing as much population to peripheries due to the growing attractiveness of cores.

> Having shown a certain capacity to retain population during the economic crisis phase, cores became attractive to international migration once again between 2015 and 2019, compensating for the reactivation of suburbanization flows. In fact, some migratory flows, such as those to large cities, were never interrupted. Consequently, during the postcrisis phase, growth became positive in the four cores. As previously explained, Seville is the only exception because it attracted less international immigration. Changes in the city of Madrid are particularly outstanding, as after experiencing the highest population decrease of all five cores between 2011 and 2015, it had the strongest increase in the following period.

> In Madrid, Barcelona, and Valencia FUAs, suburban peripheries grew once again. However, those of Bilbao did not undergo many changes, as some municipalities that lost inhabitants in the crisis period were now gaining it (and vice versa). In fact, the population figures of the Bilbao FUA as a whole (core plus rings) remained quite stable. By contrast, the suburban municipalities of the Seville FUA generally grew to a lesser extent or even decreased in the second period, with western peripheries being the only exception.

**Figure 4.** CAGRs by municipality (for each of the five FUAs) in 2011–2015 (**left**) compared to 2015–2019 (**right**). Source: 2011, 2015, and 2019 Padrón Continuo (Continuous Population Register) microdata, INE.

The peripheries of Madrid, Barcelona, and Valencia FUAs show novelties that demonstrate that post-crisis population growth was not just a replication of the economic expansion phase prior to the Great Recession. In addition to the economic crisis and its effects, the generations moving out of their parents' home at this time were also smaller than those leaving them at the beginning of the 21st century: These were the Spanish baby boomers, the largest cohorts ever born in the country. Therefore, peripheries did not grow as much as they did then. Moreover, all three metropolitan areas contain locations, generally situated at metropolitan fringes, that continued to lose population during the post-crisis phase, as they did in the previous economic crisis era. These are typically small municipalities that incorporated late to suburbanization flows during the economic expansion phase and, being located far from urban cores, were not very attractive to residential movers. The housing market of these metropolitan fringes is far from being as attractive as it was during the housing bubble.

These results refer to the total population growth or decrease in cores, rings, and whole FUAs. However, there are significant differences in the spatial patterns of population growth and mobility according to age, nationality, marital status, and type of household, as explained in the theoretical framework. This has been investigated in other publications by the authors [22,49,74]. For example, although young families continue to suburbanize, some recentralization is observed among those around 50 years of age, and even more so among the youth (20–29 years). In contrast, those over 80 years of age continue to show a trend towards suburbanization: they leave the city to live with their descendants or in residential homes for the elderly in the periphery [95]. These dynamics are shown more clearly in Barcelona and Madrid and are less distinct in the other three cities [5].
