About 80% of workers who are responsible for servicing UPS's fleet of planes took part in the vote, and of those, 98% voted to authorize a strike.
The decision comes after three years of negotiations with UPS over the workers' wages and health benefits.
If the workers go on strike, it could halt UPS's global shipping operation.
But it's unikely that a strike will happen during the holiday period, when UPS is expected to ship at least 700 million packages.
"Our customers remain in good hands with UPS throughout the holidays," UPS spokesman Mike Mangeot said. "Any kind of job action would be illegal under US labor law."
Under the US Railway Labor Act — which governs the maintenance workers — the union representing the workers must have government approval to go on strike. A board of officials appointed by the president would be responsible for making that decision, and that process can take up to 30 days.
The union representing the workers — Teamsters Local 2727 — say the biggest issue in the negotiations is related to health care.
According to the union, UPS is proposing a reduction in health benefits for the maintenance workers and retirees.
"Under UPS’s proposal, health coverage for a retiree and his or her spouse would skyrocket to more than $19,000 per year in the first year with further increases each year thereafter," the union wrote in a release.
"No one wants to go on strike, but I voted to strike because UPS mechanics and our families deserve better from UPS," Jim Kelley, a 29-year aircraft mechanic at UPS’s Louisville, Kentucky, gateway said in a statement.
(Hayley Peterson - Business Insider)