This statement is true. Developing countries indeed tend to have more people in urban areas than rural areas. For example, New York City has the massive population in the state of New York, compared to its rural areas upstate.
The developing countries have more population residing in the urban areas than in the rural areas. This is because they have more resources and have greater future perspective in terms of job and career. The developing countries have better space utilization in the urban areas and more people tend to live there because of the facilities available there.
