There were three main factors that caused the rise of Progressivism.
First, there was the economic boom and growth of industrialization that came about at the end of the 19th century and the beginning of the 20th century. This boom created huge companies and an economy in which many workers worked in large factories. It also brought about intense competition between businesses and the need for them to be as efficient as possible. These factors meant that workers were getting to be mistreated and consumers were sometimes being harmed as firms cut corners in an attempt to make money. This led to a desire for reform.
Second, there was a massive influx of immigrants during this time. The immigrants were often poor and uneducated and lived in slums in the big cities. They had ways that were unfamiliar to Americans. They also became the basis of the power of the “political machines” in the cities. The squalor in which they lived led some to want reforms in that area. Others wanted to reform their habits and ways of life. Still others wanted to do away with the corruption of the machines.
Finally, there was the rise of the middle class. The new economy created a large and growing middle class which was educated and socially conscious. Many women in that class were educated but did not have jobs. These people became the organizers of the reforms of the Progressive movement.
In short, the Progressive movement came about because there was a perceived need for reform and a new middle class to push for those reforms.