Strikes in manufacturing are known to be highly concentrated in a small number of plants. This study extends the analysis of strike concentration to coal mining and is the first study of strike concentration with significant temporal scope. The authors show that strikes were also highly concentrated in coal mining; that the prevalence of recorded strike activity was far from complete; that there was a rapid turnover in the population of highly strikeprone collieries and places; and that persistent strike activity was rare. These results afford a new perspective on strike concentration, the research implications of which are drawn out in the final section.