If I were to remove one USD bill, I would choose the $1 bill. This decision is primarily rooted in efficiency and environmental factors. The $1 bill is the most commonly used and thus deteriorates the quickest, averaging a lifespan of about 22 months. Converting the $1 bill into a coin could lead to long-term cost savings, as coins have a significantly longer lifespan than paper currency. Other nations, like Canada and Australia, have made similar changes to their currency and experienced positive outcomes. However, it is crucial to conduct thorough consumer research, as past efforts to introduce $1 coins in the US faced public pushback due to perceptions of the coins being cumbersome and impractical.