A City Council discussion on whether to limit cannabis retailers in Northampton ran into a tricky barrier at multiple points Monday night: clear data was hard to come by on if the influx of pot shops in the community has impacted young people, motorists and public health.

The council has in recent weeks prodded the idea of capping the number of marijuana dispensaries in the city. In the nearly four years since cannabis became recreationally legal in Massachusetts, Northampton has seen an influx of dispensaries unlike any other community in the state. There are 12 pot shops open and operating in the city of 29,000, all clustered within a mile of the downtown area.

According to city leaders, few residents complained about the dispensaries as one after another dotted the city center. But in August, it was the possibility of the newest dispensary Euphorium, proposed in the village of Florence that swelled public opposition from a portion of the populace.