The world's major urban areas are distributed globally but are increasingly concentrated in developing countries. Over the last 50 years, there has been a rise in the number of million-person cities due to global urbanization processes like industrialization and economic shifts. Urban development has historically progressed from pre-industrial administrative centers to rapid growth during industrialization to suburbanization with improved transportation and recent post-industrial and automobile-centered development. Current urban trends include population losses in some cities, very rapid growth in African cities, and modest expansion in others.