They join thousands of Teamsters in New York who announced a strike on Friday.
The union had given Amazon until Monday to come to the table and bargain for a contract.
Teamsters said the retail giant ignored that deadline.
Amazon has filed a legal challenge. An Amazon spokesperson said Teamsters threatened and attempted to coerce Amazon employees and third party drivers.
"The way Amazon treats its workers is un-American," said Teamsters General President Sean M. O'Brien. "Amazon's so-called 'leaders' should treat their workers fairly - they just want to put food on the table for their families. Instead, Amazon executives risk ruining the holidays for their customers because of their addiction to putting profits over people."
Amazon spokesperson Eileen Hards said in a statement, "For more than a year now, the Teamsters have continued to intentionally mislead the public - claiming that they represent 'thousands of Amazon employees and drivers.' They don't, and this is another attempt to push a false narrative about the independent small businesses who deliver on our behalf. The truth is that the Teamsters have actively threatened, intimidated, and attempted to coerce Amazon employees and third-party drivers to join them, which is illegal and is the subject of multiple pending unfair labor practice charges against the union."