Colorado Walmart employees and supporters, part of nationwide protests, in front of a Walmart store in Lakewood, Colo., on Friday, Nov. 29, 2013. 

(AP Photo/Brennan Linsley)

After years of expressing anger over low pay, workers at Walmart are getting a raise. And on Wednesday, adjunct faculty at universities across the country are planning a national day of action to "insist on fair wages and better working conditions." 

In the past, labor unions would have organized these types of campaigns to fight for better pay and working conditions. In these two instances, however, it's not -- neither Walmart workers nor adjunct faculty are widely unionized.

In Colorado, union membership rose slightly last year, but it's still low compared with past decades. Nationally, about 30 percent of workers were unionized in the early 1950s, according to Ray Hogler, a business professor with Colorado State University. Now about 11 percent of workers are unionized across the country. In the state, less than one in 10 wage and salary employees are in a union.

Labor unions went into steady decline in the last three decades for many reasons, including successful fights against requiring unionized employees to pay dues, known as the "right to work" movement. Hogler argues that the decline of unions has contributed to growing income inequality in the United States. Working Americans have lost ground on the higher standard of living to which they grew accustomed after the war, he adds.

On Colorado Matters today, Hogler talks with host Ryan Warner about some of the latest labor contentions and his new book, "The End of American Labor Unions." 

Guest: Ray Hogler, Colorado State University professor of labor law, labor relations, and human resource management.