Caterpillar's decision to slash 200 jobs in Tasmania has been likened to Ford pulling out of Geelong.
The machinery maker will restructure the production of underground mining equipment at its Burnie plant within months, moving part of the operation to Thailand.
Unions and the local council are estimating up to 4000 households will be affected directly or indirectly in the northwest region already savaged by manufacturing closures and unemployment.
"I liken it to Ford pulling out of Geelong," Burnie Mayor Steve Kons told AAP.
"You have to consider the multiplier effect, and that will be close to 1000 jobs overall."
The Ford car company announced earlier this year it would end its near century-long presence in Geelong by 2016.
Caterpillar's move is the latest hit for manufacturing in Tasmania's northwest, which has lost hundreds of jobs in recent months and has the state's highest unemployment rate.
The Caterpillar plant's permanent workforce is expected to be halved, adding to the loss of around 200 casuals since last year.
The news comes hot on the heels of a decision by vegetable manufacturer Simplot to downsize its casual workforce and give its Devonport plant three years to become financially viable.
Tasmania's Liberal opposition called on Premier Lara Giddings to take responsibility for a "black day".
But the Australian Manufacturing Workers Union said the Abbott government should have matched an election pledge from Labor to inject $10 million into the company.
"That could have made a bit of a difference, but obviously the Abbott government decided not to do that," AMWU state secretary John Short said.
Mr Kons blamed Australia's manufacturing woes on free trade, while the union said an emphasis in Tasmania on tourism and hospitality jobs wasn't working.
"(Caterpillar's were) jobs where you could bring up a family, buy a house," Mr Short said.
"I wouldn't think that many people can do that on a bit of casual tourism or hospitality work."
Sacked workers were likely to join the legion of Tasmanians taking to interstate fly-in, fly-out work, he said.
Caterpillar, which boasted sales and revenue of $60 billion worldwide in 2011, said the plant would continue to make three models of loaders and trucks.
"This shift in production will allow us to streamline the Burnie manufacturing footprint and focus on the production of underground mining machine models that are largely used within the Australian market," Burnie manager Dan Barich said in a statement.