in comparison to other Western countries. A study of US oil booms finds positive effects on local employment and income during booms but that after the boom, incomes "per capita" decreased, while "unemployment compensation payments increased relative to what they would have been if the boom had not occurred." Tradeable sectors A 2019 study found that active mining activity had an adverse impact on the growth of firms in tradeable sectors but a positive impact on the growth of firms in non-tradeable sectors. Other effects Natural resources are a source of economic rent which can generate large revenues for those controlling them even in the absence of political stability and wider economic growth. Their existence is a potential source of conflict between factions fighting for a share of the revenue, which may take the form of armed separatist conflicts in regions where the resources are produced or internal conflict between different government ministries or departments for access to budgetary allocations. This tends to erode governments' abilities to function effectively. Even when politically stable, countries whose economies are dominated by resource extraction industries tend to be less democratic and more corrupt. Violence and conflict A 2019 meta-analysis of 69 studies found "that there is no aggregate relationship between natural resources and conflict." According to a 2017 review study, "while some studies support the link between resource scarcity/abundance and armed conflict, others find no or only weak links." According to one academic study, a country that is otherwise typical but has primary commodity exports around 5% of GDP has a 6% risk of conflict, but when exports are 25% of GDP the chance of conflict rises to 33%. "Ethno-political groups are more likely to resort to rebellion rather than using nonviolent means or becoming terrorists when representing regions rich in oil." There are several factors behind the relationship between natural resources and armed conflicts. Resource wealth may increase the vulnerability of countries to conflicts by undermining the quality of governance and economic performance (the "resource curse" argument). Secondly, conflicts can occur over the control and exploitation of resources and the allocation of their revenues (the "resource war" argument). Thirdly, access to resource revenues by belligerents can prolong conflicts (the "conflict resource" argument). A 2018 study in the Journal of Conflict Resolution found that rebels were particularly likely to be able to prolong their participation in civil wars when they had access to