Image caption Gil Edmondson at Zingo's where business is down 40%

It used to be tough to get a table for breakfast at Zingo's Cafe in Bakersfield.

Truckers and young "roughnecks" from the oil fields packed the diner, which is known for its biscuits and gravy and massive portions.

But business is down 40% "since the oil went to hell" over the last 18 months, says Gil Edmondson, who owns Zingo's with his wife.

"If there's nothing going on at the oil fields, then there's not much going on here," says Edmondson. "That's our customers."

Black gold is the lifeblood of this blue-collar, conservative county - the heart of California's billion-dollar oil industry. This is the home of country music legends Buck Owens and Merle Haggard, who sang of the working man's blues.

Thousands of "nodding donkey" oil pumps dot the flat, blistering hot landscape.

Trump's promise

It's a place where young men could earn a decent middle-class living in the oil fields without a university education; where the many orange, almond and grape fields have provided work for transients since Dust Bowl migrants came here for refuge in the 1930s.

It's also a place where Donald Trump's promise to "Make America Great Again" resonates.

"We need to bring companies back to America," says Dwain Cowell over breakfast at Zingo's. Regular customers nod in agreement as Cowell rails against the loss of the US iron industry to Vietnam, China and Japan.

Image caption Dwain Cowell: "We need to bring companies back to America"

Sporting a Zingo's baseball cap, Cowell holds court in one of the booths at the cafe - his booming voice rousing other customers as they bemoan the rise in crime over the last two years because of unemployment.

Global agenda

At 81, Cowell has done well running a refrigeration business for buses and trucks, and his children and grandchildren have gone to college. But he fears for the younger generation in Kern County, where more oil is produced than in any other county in the United States.

He believes the Obama administration and Hillary Clinton are pushing a global agenda and a global economy when "we should be putting America first" and protecting industry.

A retired oil man at the next table couldn't agree more.

"We can't all be computer geeks," he shouts.

Image caption Zingo's has seen a 40% drop in business over the last year and a half

The restaurant's tables are decorated with ads from local businesses - oil companies as well as the local mom and pop operations which service the industry: trucking, air conditioning, construction.

"My old man was laid off from the oil fields," a waitress named Crystal says. A customer says he was forced into early retirement. Another customer found work driving a truck for a fraction of the pay he was earning in the oil fields.

"Women are the only ones still working around here," another waitress says. "And our business is way down."

The oil crash

As other Americans embrace lower oil and gas prices with road trips, in Kern County every sector of the economy is suffering the effects of low oil prices and mass lay-offs in the industry.

A barrel of oil cost $100 in June 2014. US oil prices crashed to $27 a barrel in January - the lowest level since 2003. With prices now hovering at around $50 a barrel, oil producers are still holding off from rehiring many of the laid off workers.

Employment in Kern County's oil and gas extraction and well drilling is down 17.6% compared with a year ago, according to state figures released in June.

The overall unemployment rate in Kern County was 9.7% in May, more than double California's 4.7% rate and 4.5% for the US.

Not everyone in Bakersfield is a Republican, but it's hard to find Democrats at the local bars and diners. Local radio is dominated by conservative talk shows - Rush Limbaugh and local hosts who have many nicknames for the political elite: Killary, Crooked Hillary, Lyin' Ted.

Image caption Bakersfield is in the San Joaquin Valley of California

President Obama is still "accidentally" called "Osama" and dismissed as a Muslim and a foreigner doing irreparable damage to America's standing in the world.

'We're all struggling'

Many here feel excluded from the positive economic data being touted in Washington. Kern County weathered the 2007-08 financial crisis better than most: at a time of high oil prices many were getting into the oil industry while it was booming.

And the oil industry pays well.

At the peak of his career as an oil consultant, Patrick McGonigal earned nearly $300,000 a year. He lived the high life, owning a Corvette, a custom Harley and homes in Bakersfield, North Dakota and San Diego.

Image caption Patrick McGonigal, pictured with his girlfriend Shannon, says he and others are concerned about their futures

Now he's effectively homeless - couch surfing with family and friends. The Corvette, hog and homes long gone since oil prices tanked over the last 18 months - the worst drop in oil prices in a generation.

"We're all struggling," he says. If the price of oil doesn't dramatically rise, he says, many here don't know how they'll survive.

The downturn has hit every generation of McGonigal's family. His stepfather is also an oil man and was forced into early retirement. Several other family members are unemployed and living off their savings.

Five-year drought

Many here feel like the government is leading the country into decline, by not protecting the oil and gas industry or doing more to support American manufacturing and farming.

Image caption Agriculture has also been hit - by drought

A five-year long drought hasn't helped - agriculture is the other major industry here and it is suffering as farmers grapple with the cost of water.

This is also Steinbeck country - where the fictional Joad family came in The Grapes of Wrath after fleeing Oklahoma in search of a better life.

Instead of finding paradise, the desperate "Okie" migrants of the 1930s were treated with suspicion in Bakersfield, much the way Mexican farm workers are treated today.

Instead of a promised land of plenty, they struggled to find even low-paying, backbreaking jobs on farms and many starved to death.

Good old days

Donald Trump's promise to build a wall between the US and Mexico is a popular prospect here.

Image caption Derrick Nichols remembers the good old days outside Long Branch Saloon

Unemployed carpenter and oil field worker Derrick Nichols, 29, says it's difficult to get a job if you don't speak Spanish, which he doesn't.

In the middle of a hot day, he sits at the bar of the Long Branch Saloon in Oildale - a rough neighbourhood a few miles north of Bakersfield where gangs and drugs have created opportunity for some who have lost out in the oil economy.

He talks of the good old days in Oildale when he was a kid. There used to be a dairy just down the road and the river was clean and kids used to ride their bikes freely throughout the neighbourhood.

"Now we can't let our kids out of our sight. There's too many tweakers out there," he says of the drugs, which have destroyed so many lives here.