Hoover Dam<span>, once known as Boulder Dam, is a concrete arch-gravity dam </span>in<span> the Black Canyon ....</span>Construction<span> of a rail line joining Las Vegas and the dam site began </span>in<span> September </span>1930<span>. .... Falling objects were the most common cause of death on the dam site; the highscalers' work thus </span>helped<span>ensure</span><span> worker safety</span>
A "Formal Amendment" is one that actually adds to or changes the US Constitution. It is ratified by the states and becomes law.
An "informal amendment"is a change to the meaning or interpretation of the Constitution of the United States. There is no real informal way to change the Constitution, and it's not an actual change to the wording of the Constitution; rather, it's the way we perceive the Constitution that changes.
The one that comes to mind is the equal rights amendment (1972) - which prohibits the inequality of men and women. Opponents say that the amendment is no longer needed, as the issues
The reason that printing currency is a delegated power is because, our Nation needs to be able to trade among itself. If two states had different types of currency from one another it would make trade and travel between the states much more difficult as money from FL and NY would likely be different and likewise useless in each of the other states.