Final answer:
During the late 1860s, urban development was fostered by the transition from dependence on waterways for power and transportation to the advancements of industrialization and railroad construction. Technological innovations and economic growth were key drivers for this change, leading to an increase in urban migration and the growth of cities.
Step-by-step explanation:
The late 1860s saw a transformation in urban development, particularly as cities began to grow away from waterways. This was not due to major freeways or the development of air conditioning, both of which came later but was primarily driven by improvements in industrialization and the transformation brought by the steam engine. Factories no longer needed to be situated near waterways for transportation or water power, allowing them to be located closer to urban centers. The subsequent job creation led to an increase in urban migration. Furthermore, the construction of the railroads played a significant role in connecting distant areas and facilitating economic growth, thus driving urbanization.
Other factors included advances in technology and economic conditions. Innovations such as electric lighting, communication improvements, intracity transportation, and the rise of skyscrapers were pivotal. These advancements, along with strong social organization and the ability to support a growing nonfarming population, contributed to the urban explosion. However, as cities became more crowded, issues such as proper sanitation and fresh water supply surfaced, creating new challenges for urban living. The rise of suburbs and later exurbs reflected a move towards areas that offered more space and lower costs, yet still provided access to city jobs.