Please correct and comment my summary about overpopulation

Over the past century, there has been a dramatic increase in the number of people in big cities, leading to a variety of negative effects on people's lives. The most important one is unemployment, which is a direct consequence of the rise in the urban population. That the number of people who lack jobs is increasing immensely. Due to over-crowding, there are not enough available jobs for all of them. China can be considered as a typical example of overpopulation, where regularly has a high number of jobless people. The second major result of the density of population is the shortage of accommodations. The more people living in one place, the more land is needed. Unfortunately, many people are unable to find a place to live in, which is a step back for the city’s development. That is the reason why more and more slums are appearing now. Finally, traffic jams are also believed to be a consequence of over-crowded areas. In most countries, drivers have to face congestion in peak hours for long hours in order to move. Not only does overpopulation result in congestion, but the smoke and emission from vehicles also have bad impacts on people's health. To sum up, so many bad effects of overpopulation have created the need for government and individuals to take urgent actions to tackle the rapid growth of this problem.