"कितने आदमी थे?" बहुत, सरकार | A migration-thread with estimates of India's reverse migration since mid-March 2020, placed conservatively at 30 million or 3 crore or 15-20% of the urban workforce. 
Phase 1, just before the lock-down, saw people go back for the Holi festival. A conservative estimate of 5 million based on old passenger traffic data as the number that stayed on, mostly within-state migration.
Phase 2 (Mar 25-Apr 30) started with a rush, esp. from Delhi and other places where some state govts. did arrange for buses. Based on numerous reports on this and district-border crossings, I estimate 5 million as a very conservative number, mostly within-state migration.
Phase 3 in May, with Shramik Trains (5 million people) and road transport options saw the maximum exodus, with 20 million as a very conservative figure, most of which is inter-state migration. People from abroad (Vande Bharat Mission) is less than 100K.
One way to gauge Phase 3 numbers is by looking at Gujarat for which various numbers exist, as shown in the slide. Using Gujarat's share in inter-state migrant workers as 10% and the information that about 3 million left, leads to upper-est. of 30 million for inter-state-mig alone
The Shramik Trains data is very useful because its the only firm number available, across states. For future planning, note the magic number of 1,338 as people transported per train!
The 30 million estimate (20 million+ interstate) is very conservative as the bulk of movements are intra-state which are hard to document. Most of it is from urban areas, and the 15-20% shortage of workforce will bid up labour costs in the coming months.
While the bulk of the 30 million estimate refers to adult men, the number of women and children easily runs into a few millions. Will this reverse migration be reversed? Mostly, yes, but can be fast-tracked with a lot of assurances and incentives on wages, safety and health.
