I would say that industrialization was the economic force that had the most to do with this new wave of imperialism. It made imperialism both more possible and more necessary.
Imperialism became more possible as things like steamships and the telegraph made long distance travel and communication easier and faster.
Imperialism became more necessary as countries sought new markets for the goods that they could now create in abundance and as they sought new sources of the raw materials that they needed.
These two factors made it much more likely that European countries, the US, and eventually Japan would try to become imperial powers.
There were economic forces that led to a new wave of imperialism between 1850 and 1920. One of these forces was the desire for resources. As the industrial revolution expanded, countries wanted colonies for a few reasons. One reason was they could get resources cheaper from their colonies than they could if they bought those resources from other countries. Having colonies also gave a country a guaranteed market where it could sell its goods and make money. This arrangement would help the colonial power’s economy at home.
Another economic factor was that having colonies made it easier for countries to protect their merchant marine and their world trade. Colonies could serve as places for the navy to use to dock their ships and resupply them. They could also use the colonies as military bases if it was necessary to take military action to protect their world trade and their merchant marine. Protecting world trade was important for economic growth.
By establishing colonies worldwide, a country could enhance its status as a world power. Being a world power could open other economic opportunities for the country that may allow their economy to grow. New trade opportunities could develop or reciprocal agreements could be made with other world power nations and their colonies. Preferred trading status could be developed through such arrangements.
There were many economic forces that encouraged a new wave of imperialism between 1850-1920.
There are multiple elements leading to the "new Imperialism" of the late 19th and early 20th centuries. Among the purely economic elements were:
- Transportation had entered a self-perpetuating growth spiral that worked like an engine to drive both territory-based imperialism and investment-based imperialism. Nations and individuals could travel and expand their territory, and use that territory as a basis for investment and growth.
- Military improvements made geographic expansion into low-tech territory "cheap" in terms of both blood and treasure. A few well-armed soldiers backed by a well-supplied army could take and hold vast amounts of land in undeveloped regions.
- Undeveloped territories presented huge economic temptation in terms of cheap land, cheap labor, and cheap natural resources.
- These temptations were true not only for businesses and nations, but for individuals. The potential returns for all classes of Europeans who invested small capital backed with huge amounts of labor opened the doors to possibility that had grown in the minds of the common citizens starting in the first era of expansion during the late Renaissance and early Baroque era. New access to education prepared common citizens with a greater hope of successful management of property and wealth. The result was a huge flood of well-prepared settlers and entrepreneurs ready to expand into undeveloped lands.
- The economic advantages of a stable government also called to many European nations--England in particular. The British dream of an "Empire on which the sun never sets" was a dream of world-wide stability of government and trade, focused on England but benefitting all the world...a benefit many have argued was pure arrogance and greed ever since. Still, the idea of one world, with one shared law, and with a balance of powers such that all the world would be safe for trade and cultural expansion was very real, and based on the success already brought by economic expansion. Europeans hoped for a self-perpetuating economic growth pattern much like that in transportation: a growing, endless spiral of wealth and prosperity lifting all people out of poverty and stagnation.