Having a union makes a difference. On average, union members earn about 20% more in wages than non-union members. Because each contract can be different, a member should read their contract to find out about wages.
And wages are one part of an overall package for many union members including: health care coverage, retirement, vacation and sick leave.
The industries in the state and national economy that have the most "union density" - the percentage of union members in a particular workforce - will tend to have a stronger ability to bargain for higher wages and benefits. Organizing new worksites and new workers not only helps those particular workers get better wages, it helps all union members, especially.
Make sure you check your paycheck. If you feel that you have missed a pay raise, not been paid for time worked, not been paid properly for holiday time, etc., contact your Union Rep.