Which technological innovation was most important for early-nineteenth-century economic development?

Electricity

Explanation:

Innovation is the ability to create a new device or process, resulting from study and experiments. There were a couple innovations that came into existence in the early-nineteenth-century, but the most important is electricity.

The birth of electricity brought about a totally different means to solve man-powered labor. Hence, saving time and achieving more.

This also led to the innovation of various devices and processes that further paved way for more economic growth.