Making Change at Walmart, a campaign backed by the United Food and Commercial Workers International Union, estimates that 150 to 160 people work at each Sam's Club store, meaning the closures could affect about 10,000 people.
Earlier in the day, Walmart had cited the sweeping Republican tax overhaul that will save it money in announcing the higher hourly wages, one-time bonuses and expanded parental benefits that will affect more than a million hourly workers in the U.S.
The retail industry is seeking to fill 711,000 open jobs, the highest on records dating back to 2001, according to government data.
The company said the wage increase benefits all hourly U.S.
For the first time, Walmart also promised to help with adoptions, offering full-time hourly and salaried workers $5,000 per child that can be used for expenses such as adoption agency fees, translation fees and legal or court costs.