Did americans become involved in the pacific region in the latter half of the 19th century?

Yes

Explanation:

In the later half of the 19th century, the United States increasingly became interested in the Pacific region and aimed to build up trade as well as military might there.

Some actions they engaged in include;

The purchase of Alaska in 1867 from Russia. This ensured that the USA now had a foothold in the northern Pacific region from which they could spread out.The acquisition of some territories in the Pacific as well as gaining control over certain colonies. For instance, following the Spanish - American war, the US acquired both the Philippians, Hawaii and Guam in 1898 and as well as encouraging settlement, built up military basis there with Hawaii coming to be the base of the very important and famous, Pearl Habor Navy Station.Engaging in trade with the Japanese and the Chinese. Previously, the Japanese did not allow foreign ships in their shore. President Millard Fillmore sent Commodore Matthew C. Perry in 1853 to force the Japanese to open their shores up for trade which the Commodore accomplished using Gun-boat diplomacy (showing the superiority of your navy by firing weapons into the sea to scare your opponents). In the subsequent Convention of Kanagawa in 1854, the Japanese allowed the Americans to trade in 2 ports. As for China, the United States instituted the Open Door Policy with other European countries that called for equal trading rights to all countries trading with China to enable them have the same access that other nations did to the vast Chinese market.