Urban migration, or the movement of people from rural areas to cities, began as a result of industrial development. The growth of factories and industries in cities created job opportunities, attracting people from rural areas who were seeking better economic prospects. The presence of factories and industries also led to the development of other urban facilities and services, making cities more attractive places to live. As a result, people began moving to cities in large numbers, leading to the growth of urban populations and the development of large cities.