of the (male) household head being a nonresident, possibly because that leaves family members of the migrant who are left behind more vulnerable.

The deterrent effect of distance, combined with the role of an established network in destination areas, can reinforce the lack of mobility for those residing in remote locations. An idiosyncratic decision to move to where no one has gone before initiates the establishment of a network. Given that distance acts as a deterrent, the cumulative effect of this is to have remote rural settlements that become isolated from the migration process. This cumulative inertia then denies these more remote locations any of the benefits that may emerge from having fellow villagers or family members in town, leaving them disconnected from progress in the central core of the economy.

There is also a possible administrative dimension to interstate migration barriers, as a result of domicile provisions for work and study, lack of portability of social benefits, and legal and other entitlements upon relocation. Although anyone in India is legally free to move from one location to another, policies implemented at the state level can inhibit the mobility of labor across state boundaries. This includes poor interstate portability of identification documents, which means that migrants risk losing access to social protection. The lure of reserved seats on state educational institutes and public sector jobs could also keep people from moving across states. Looking ahead, internal migration might be constrained less if the central government contribution to social welfare benefits increases or if states are legally obliged to grant the entitlement to social protection to migrants. For the latter, elementary education, which now invokes a constitutional guarantee, is a case in point. Continued progress on the national “Unique Identity Documentation" project will also be a factor, because the bureaucratic processes involved to surrender a ration card issued by the origin state, and obtain a new one in the destination state are complex, and often prone to corruption and administrative errors (Abbas and Verma, 2014).

For future research, there is need to improve databases on internal migration. Traditional migration data, based on the Census and household surveys conducted by India’s NSSO, are often outdated, due to their limited frequency and lag in publication. The Census is conducted once every decade, which is understandable given the scale of the exercise. Yet, the speed of data dissemination can potentially be improved considerably; for instance, migration data from the 2011 Census are still not publicly available. In the case of the migration module conducted by India’s NSSO, the latest available survey is from 2007-08. Prior to this, much like the modules on employment and consumer expenditure, the migration round was completed every 4-5 years. Therefore, there is the possibility to renew the earlier frequency of the NSSO’s migration survey.

Further, there is the issue of questionnaire design. The biggest inadequacy of migration data based on the Census and NSSO household surveys, especially the former, is the fact that they do not accurately capture circular labor migration, which is prevalent in both short- and long-term migration streams. Another weakness of the Census/NSSO surveys is the fact that different types of migration are measured on the ‘principal’ reason basis. For instance, female migration for work is concealed in ‘reason-for-migration’ statistics because the principal reason given to the enumerator is ‘marriage’ or ‘moved with household.’ Unlike the conventional data sources, The IHDS tracks the same households over time and this availability of panel data could potentially improve the analysis on migration dynamics. It is also 22