Iselin is the fourth most populous neighborhood in Basel, home to 18,044 residents across a surface of 1.1 square kilometers, an average-sized area that places it at the western edge of the city, bordering Allschwil and France.

The most distinctive finding about Iselin is its exceptionally low share of long-term residents, or "Sesshafte," at just 31.0 percent, the lowest of all 21 neighborhoods in Basel. This indicates a highly transient population, where people move in and out frequently, far below the city average and suggesting a dynamic, ever-changing community.

Geographically, Iselin is an average-sized neighborhood covering 3.0 percent of the canton's total area, ranking 10th in size. Its population is notably diverse, with 40.6 percent foreign nationals, ranking 11th, and a balanced age structure: the youth dependency ratio of 27.2 percent is exactly at the city median (rank 10), while the old-age dependency ratio of 24.4 percent is relatively low (rank 16), meaning fewer elderly residents compared to other parts of Basel.

Socially and economically, Iselin presents a mixed picture. The share of welfare recipients is 6.6 percent, which is moderate, and the unemployment rate stands at 4.6 percent, also around the middle of the pack. However, the neighborhood stands out for its high share of green space at 37.2 percent, one of the highest in the city, and its relatively spacious living conditions: the average apartment size is 69.0 square meters, and living space per person is 37.2 square meters, both above the city average. The average building construction year of 1939 reflects a housing stock that is older than in many other neighborhoods, contributing to the area's established character despite the high turnover of residents.