Why does the tenth amendment use the term reserved to describe the powers to the people and the states?

What is the name for the main idea behind the settling of western lands by americans in the early-1800s?

In what ways could globalization possibly impact negatively and/or positively your current or future work environment

The rise of advertising in the 1920s. i am good with seeing how advertisements shape the roaring twenties and how it developed a new way of life through modern days. but i am not sure what the details of advertising in the 1920s were. if possible can you send me links (preferrably credential links) to sources that maybe show like the first company to start advertising through the radio, how advertising benefits (statistics graphs), etc.