Soil conservation refers to preventing erosion of the soil's top layer, as well as decreasing fertility due to overuse, acidification, salinization, or other chemical soil contamination.
committee membership contribute to the incumbency advantage as assignments from such membership can be used to legislate issues that are really important to their state or districts. By legislating issues critical to the constituency, the incumbent is likely to appeal to voters hence high probability of reelection
science can help improve technology and this can allow a civilization to grow and flourish better and save lives of sick and injured
This is a tough question because the answer depends on when and where. If you are just worried about who was there first, then the answer should be the Franciscans who worked from 1526 [when the pope declared the Native American Indian capable of understanding Catholicism] to about 1573 which is when hundred of missions were present in Florida and New Mexico.
Later on California had 21 missions along the El Camino Real (from San Francisco to San Diego).
The idea of Manifest Destiny arose in response to the prospect of U.S. annexation of Texas and to a dispute with Britain over the Oregon Country, which became part of the union. Manifest Destiny was the idea that white Americans were divinely ordained to settle the entire continent of North America. The ideology of Manifest Destiny inspired a variety of measures designed to remove or destroy the native population. Weeks has noted that three key themes were usually touched upon by advocates of manifest destiny: the virtue of the American people and their institutions; the mission to spread these institutions, thereby redeeming and remaking the world in the image of the United States; the destiny under God to do this work. Manifest Destiny increased goods and doubled the U.S.'s land area, services, and wealth. In addition to that, with the territorial expansion, more ports were opened along with Asia and Europe, and it was very beneficial to the country since it brought a lot of wealth to the country's economy.
- I hope this helps