International migration research has long been hampered by a lack of data. Although we have a general idea about the level of international migration and how it varies over time, migration scholars have tended to focus their study on those areas and in those times for which data have been most readily available. This is problematic for the study of emigration and political development, in at least two important ways. First, it is difficult to say anything useful about the effects of emigration on political development if we do not have systematic evidence of the level of and variation in international emigration over time. Indeed, I find it both insightful and embarrassing that policy makers have exerted so little energy to track international migration flows relative to global trade and financial flows, for example. The first place to begin any study of the effects of international emigration must be to document the extent of that emigration over time and across countries.

Second, the current limited focus of research is problematic because effects of emigration vary across migration regimes. Because we can expect the effects of emigration to vary with the extent of emigration (as described in the preceding chapter), and because the extent of emigration is likely to vary along with the opportunity to do so, then the political effects of emigration might be stronger at times when the global migration regime is more accommodating to migrants. In other words, the political effects of emigration should be strongest when the opportunity to emigrate is greatest.