Intern Zach McEntire here, or "Z" as Richie sometimes calls me. I recently talked to the historians of the Utah Historical Society concerning the name and history of 300 S. Street, or more commonly known as Broadway.
According to an article in the old Salt Lake Telegram (former newspaper publication), the idea to change the name to Broadway was proposed and petitioned by multiple local businesses and department stores that relocated to Broadway from Main Street. During the time, there were a lot of updates and changes made to the street, accoridng to the article, "[T]he changes that have been made in the Third South street skyline during the last few months, and the transforming of the thoroughfare from a 'back street' into one of the potentially greatest and busiest streets of the city, by reason of the contemplated transfer of a number of the largest department stores of the state, and other big businesses from Main Street loaction to the new shopping district, persons who revisit Salt Lake City wihtin the next year...will be compiled to ask one of the neatly unifromed policemen...if they dropped from the train in the wrong town."
However, there were some who were opposed to the name change. According to another article in the Telegram, the Post Office doesn’t agree with the name change stating, “If the name Third South is changed to Broadway it will set a new precedent. New names will be creeping in and taking the places of all our good old-fashioned names. It's all right to name streets after our New Yorkers and brethren from other cities when we can find no other names suitable, but this idea of uprooting our foundation of street names is painful to me.”
At the time, the petition was turned down by the city comission, they thought of it as “ill advised.” So, business owners simply referred to the street as Broadway and after decades of the street being called Broadway, the titlewas added as an additional address name.