The "A127 50mph Speed Limit Protest!" group – which blasts the introduction of a 50mph limit enforced by Essex's first set of average speed cameras, as "a money making hazard" – won 1,000 members within just three days of being set up on January 16.
At the last count it had more than 9,100 members and is increasing every day.
Creator Katie Shergold, 23 from Leigh-on-Sea, said: "I never dreamed it would have such a strong response.
"I felt so strongly about the new speed limit and average speed cameras that I felt I had to do something.
"When I first had the idea of starting a petition or campaign I didn't know how to go about it. As soon as I thought of Facebook, I knew it would be a brilliant way to gauge people's feelings and see what reaction and option people gave."
The group has already been inundated with 556 comments and hopes to force Essex County Council into a U-turn over the introduction on January 15 of cameras on the stretch of the A127 between Nevendon, near Wickford, and the Southend-on-Sea boundary.
The council claimed the measure was needed after nearly 500 deaths or serious injuries occurred on that stretch in the past five years.
But many of the contributors to the Facebook site believe the scheme, enforcing the national limit along a 4km stretch of the A127 between Nevendon and the Dick Turpin pub and a new 50mph limit between the Dick Turpin and the Southend-on-Sea boundary, is causing more trouble than it solves.
Speedo
Jenny Bacon wrote: "When I used it the other day, I was so aware of not going over 50, I felt unsafe, spending more time watching my speedo than looking at the road
Another poster, Kerry Snowdon said: "These cameras don't do what the council thought they would. I have driven on the A127 during rush hour and these cameras haven't made any change to the congestion.
"These cameras were just another way for the council to spend all our money at a time when money is really short."
Some 155 people have already signed a petition opposing the blanket speed limit imposed on the A127 on the Prime Minister's official website.
An Essex County Council spokesman said reduced speed limits and cameras were the "safest and most effective way of saving lives".
He added: "A minority of people continue to feel they should be able to travel at whatever speed they like, but we would ask them to consider the effect of their actions on the majority of other road users, particularly on a stretch of road never designed for high speed traffic."
He added that variable speed limits were introduced because "accidents have previously occurred at all times of night and the stretch of the A127 has been proven to be simply too dangerous to allow vehicles to travel at greater speeds; this is as relevant during the night-time as during the day."
The council promised to keep the results of the new limits under observation.