Trucks were loaded at the company’s Michigan plant on Sunday morning for the drugs to be dispatched across the country.
Workers burst into applause as the vaccines were packed in coolers with dry ice and loaded onto trucks for transportation.
From the factory in Kalamazoo they were taken to Fed-Ex and UPS transport hubs around the country before ultimately being delivered to 636 locations nationwide.
Officials say that 145 sites will get the vaccines on Monday and all sites will receive them by Wednesday.
Food and Drug Administration commissioner Dr Stephen Hahn told CNN's State of the Union that the government would "hopefully" begin vaccine administration within hours.
"My hope, again, is that this happens very expeditiously, hopefully tomorrow," said Dr Hahn.
Pfizer says that all 50 states will receive some vaccines on Monday, according to NBC News. The pharmaceutical giant hopes to have shipped as many as 40 million doses by the end of the year from its Michigan plant and two other facilities.
And they hope to have delivered 1.3billion doses of vaccine by the end of 2021.
The Food and Drug Administration granted Pfizer emergency authorization for its drug on Friday and the CDC advisory panel recommended its use on Saturday.
An estimated 16.2 million people have tested positive for coronavirus in the US and more than 298,000 have died during the pandemic.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies