Epidemiology of suicide in the Tricity metropolitan area in northern Poland 1980–2009: Evidence of influence by political and socioeconomic changes

•Between 1980 and 2009, in Tri-City area, Poland, there was a rise in suicide manifested by an increased number of completed suicides.•A statistically significant correlation between the number of suicides and the unemployment rate was observed.•The sharp increase in the number of suicides in rural areas compared to urban areas is most likely to be associated with the increasing inequality in socioeconomic aspects between rural and urban areas.