The Union Membership Rate of employees vary widely across countries in Europe and the USA. In Europe, the Scandinavian countries of Finland, Sweden and Norway have the highest union membership rates. The US has one of the lowest union membership rate when compared to most European countries.
The chart below shows the union membership rate across Europe and the US:
Click to enlarge
Though European countries have high union membership rates, in general membership has been declining in recent years according to an article at ETUI. The membership rate is 74% in Finland, 70% in Sweden and 67% in Denmark. It is just 8% in France. The low rate in France is surprising. But the power of union workers is strong in France as they are able to mobilize support and launch strikes and other actions at will bringing the country to a standstill.
The only three countries that have lower membership rates than the US are Estonia, Lithuania and France. As mentioned above, French unions have more power due to labor laws and support from the general population. According to the BLS, the percentage of workers participating in unions was just 11.1% in 2015. Or to put it another way, only 14.8 million workers out of many millions belonged to a union. This is not surprising as unions have historically had bad reputation.