Amazon warehouse workers in Bessemer, Alabama, overwhelmingly voted against joining the Retail, Wholesale and Department Store Union in much-anticipated election results announced Friday.

Amazon and business groups celebrated the decision, saying warehouse workers got a chance to weigh the pros and cons of union membership – and voted to reject it.

But labor activists argue that the lopsided vote shows how unfairly the odds are stack against union organizing efforts and highlight the need for Congress to reform U.S. labor law. The House last month passed such legislation — the Protecting the Right to Organize (PRO) Act — but it looks likely to die in the Senate.

The Bessemer results “reveal a broken union election system,” Celine McNicholas, labor counsel at the left-leaning Economic Policy Institute, said in a statement. “It is clear that if policymakers do not reform our nation’s labor law system, then they are effectively denying workers a meaningful right to a union and collective bargaining.’’

The retail union complains that Amazon plastered the Alabama workplace with anti-union posters and forced employees to sit through mandatory sessions in which the company disparaged the union. Labor organizers, by contrast, had to catch employees outside the warehouse gate to make their pitch.

“The law failed the workers,” said Benjamin Sachs, a labor law professor at Harvard Law School. “The law gives employers far too much latitude to interfere in workers’ ability to make a choice to join a union. That choice should be for the workers to make, not the employers to make.”

Amazon supporters note that the company paid an average $15.30 an hour – more than double minimum wage in Alabama – and offered health care and other benefits. “Union representation is a choice for workers,” said David French, spokesman for the National Retail Federation. “But many clearly prefer opportunities in a competitive marketplace that provides strong wages and benefits.’’

Randy Korgan, of the International Brotherhood of Teamsters National Director for Amazon, rejected the idea Amazon pays competitive wages at a time when $15 an hour has become the minimum wage in some states. Korgan said he made more than $15 an hour himself as a warehouse worker in the early 1990s.

“Using the minimum wage as barometer is a huge mistake,” Korgan said. “This is not minimum wage work and for any employer to pat themselves on back and use this as a guiding post shows they don’t understand how difficult this work is.”

American unions have been declining for decades. The percentage of workers who belong to unions peaked in 34.8 percent in 1954, according to the Congressional Research Service. By last year, their share of workers had fallen to 10.8 percent, the Labor Department reported.

America’s unionization rate is one of the lowest in the world; it compares to 90 percent in Iceland, 67 percent in Denmark, 28 percent in Canada and 17 percent in Germany, according to the International Labor Organization.