The Anti-Imperialist League argued that imperialism and expansionism went against the spirit of the United States' founding documents, such as the
Constitution. Which event from the late 19th century or early 20th century
most clearly supports this argument?

The American annexation of the Philippines.

Explanation:

The Anti Imperialist League was created in 1898, in response to the annexation of the Philippines by the United States. It was, basically, a group of conservative democrats who opposed the expansionist idea once defended by Manifest Destiny, as well as the militarization and strategic expansion ordered by the main leaders of the Republican Party. Its foundation lay in the principle of freedom and consensus of the governed, by means of which they said that America would act as a tyranny to try to expand its territories, by crushing the rights of the inhabitants of those lands.

wisdom

explanation:

the fact that that the teachings on the cosmic order comes from, or through, the heart center

after the civil war, and with the termination of slavery, the south was faced with a big problem; what was supposed to happen and how they were supposed to deal with the freedom and the rights that black people and freed slaves had gained as a result of the north defeating the south and forcing the end of slavery. first, most, if not all, of the workforce of the south came from slaves and they did not have an option to replace the loss of said workforce. second, particularly in the south, people were convinced that black people were lesser, less intelligent, less capable and less smart than whites. this posed a huge problem for them. also, southerners were faced with another issue; freed slaves now had a say in how their lives would be lived and the right to politically choose the way they would be governed. people in the south did not want to accept this, none of this and this opposition and the conflicts that arose from it, not to mention the afereffects of the war, forced the congress of the time to enact and enforce the reconstruction plans that had been proposed by president andrew johnson.