what would be some reasons for blacks to leave an agrarian society during the great migration?

Answer 1

Share croppers, white and black, made little if any money for themsleves and their families. The chance to work in a city was also a chance to gain a job which actually paid something. Earning money seemed like a better life than substinence farming on land you didn't even own.

Answer 2

To follow the herds, but then the white, brown and yellow people did the same. And, if the green people would have stayed in the original form, they would have joined the trek in the stomach of a reptile.