LONDON — Most of Europe may be united through the European Union, but when it comes to illicit drugs, geographical differences could hardly be more apparent.

A new research project has examined illicit drug use in 60 European cities, monitoring consumption patterns in real time. The researchers focused on wastewater analysis, which is commonly used to estimate the average drug consumption in certain areas.

Concentrations of cocaine and MDMA, also known as ecstasy, were higher in larger cities compared with smaller towns. “More than three-quarters of cities show higher loads of [cocaine] and MDMA in wastewater during the weekend (Friday to Monday) than during weekdays. In contrast, amphetamine and methamphetamine use were found to be distributed more evenly over the whole week,” the report concludes.

In the slider maps below, you can see how consumption differs on the weekend and weekdays: On the left side, you see MDMA consumption from Monday to Friday. The map on the right shows consumption during the weekend.

Whereas MDMA use was fairly even among European countries, the consumption of other drugs was more pronounced in certain nations.

“Cocaine use is highest in western European cities, in particular in cities in Belgium, the Netherlands and the United Kingdom, and in some southern and northern European cities,” the report’s authors said. “Wastewater analysis indicates that cocaine use is very low to negligible in the majority of eastern European cities.”

A similar geographical division was found among methamphetamine users. That drug was found in particularly high concentration in Norwegian, Czech and Slovak cities, as well as in Dresden, a city in eastern Germany that is close to the border with the Czech Republic.

The differing geographical consumption patterns are clearly visible on this slider map. The map on the left shows weekend consumption of cocaine, while the image on the right visualizes methamphetamine consumption during the same time frame.