What boundaries of the U. S. mainland were formed from the 1840s to 1853

The US mainland boundary to Mexico from 1848-1853: Texas, New Mexico, Arizona, Utah and California.

Explanation:

Territorial Evolution in US mainland Border States.

1846 - Texas was annexed by the Federal Government after a Local Referendum, and approved by the US Congress.

1846 - The Northwest part of California starts to be American Territory.

1848 - The Guadalupe Hidalgo Treaty formalized the cession over territories such as (the greater part of California), (Northern part of) New Mexico. Colorado, Utah, Nevada, and Arizona. By the end of the Mexican American War.

1853 - The Gadsden Purchase was the final act to buy the southern part of New Mexico.

1840 - Fiji Islands. - July. Naval forces landed to punish native for attacking American exploring and surveying parties.