In 2023, Basel-Stadt recorded a total of 830 marriages. The average age of brides was 34.3 years, while grooms averaged 37.3 years. The youngest bride was 18, and the oldest was 81, whereas grooms ranged from 19 to 83 years old. The maximum age difference between partners was 35 years, with an average difference of 3.0 years. These figures align with historical extremes, where the youngest recorded ages were 16 for women and 17 for men, and the oldest were 90 and 95, respectively. The largest age differences historically have reached 57 years with the man older and 45 years with the woman older.

Examining long-term trends from 1979 to the present, the number of marriages in Basel-Stadt has seen fluctuations. In the late 1970s and early 1980s, marriage numbers were higher, peaking at 1365 in 1991. Since then, there has been a gradual decline, with recent years stabilizing around 800 to 1000 marriages annually. As shown in Table 1, the average age at marriage has increased over time. In 1979, brides averaged 27.9 years and grooms 31.0 years, compared to 34.3 and 37.3 years, respectively, in 2023. This shift indicates a trend toward later marriages.

The evolution of age patterns in Basel-Stadt reveals a clear shift towards older ages at marriage. The average age difference between partners has remained relatively stable, fluctuating between 2.8 and 4.2 years over the decades. As Table 1 illustrates, the average age of brides and grooms has steadily increased, reflecting broader societal trends towards marrying later in life.

Nationality patterns in marriages have also shifted significantly. In 1979, Swiss-Swiss marriages constituted 68.9% of the total, but by 2023, this share had decreased to 29.3%. Conversely, the proportion of marriages involving at least one non-Swiss partner has increased. This change reflects broader demographic shifts and the growing diversity within Basel-Stadt.

Seasonality in marriages is evident from the data, with certain months consistently showing higher marriage activity. Figure 1, the heatmap of marriages by month and year, highlights peaks in June and September, which were more stable until the late 1990s. Since then, the seasonality pattern has become less predictable, with August now showing the highest average number of marriages at 122.7, followed by September and June. These patterns suggest a preference for summer and early autumn weddings, though the consistency of these peaks has varied over time.

In conclusion, the data on marriages in Basel-Stadt reveals several key insights: a trend towards later marriages, a significant shift in nationality patterns with a decline in Swiss-Swiss marriages, and evolving seasonality in marriage timing. These trends reflect broader societal changes and the unique demographic landscape of Basel-Stadt.