What were the successes and failures of unions in the early 1900s?

Oh jeez. Where to begin?

Ending child labor. Granting women working rights. Granting ethnic minorities working rights. Mandatory safety codes to protect both workers and consumers from harmful working conditions and harmful products. Etc etc etc.

Some of the failures included becoming to politically powerful and corrupt. Unions nearly destroyed the U.S. auto industry in the 70s and 80s. Workers got lazy and over-paid.

To this day, Unions are a precarious balancing act. They have to potential to to lots of good and lots of bad.

I'm not going to spoon-feed this to you. It's too important. Look into the general history of unions and organized labor, suggesting more specifically that of the mine workers, those in the textile industry, and the IBEW. Many died to make it better for others. If you really go after it, note what was done to suppress them.