The average job in the U.S. will expand its workforce by 7% through 2026, but not all industries will be lucky enough to be adding staff in the future. About 17% of the 818 occupations the Bureau of Labor Statistics tracks will actually lose more workers than they add between 2016 and 2026. The number of metal and plastic machines workers is expected to drop 9% in that decade. While other careers, such as locomotive firers, typists and postmasters will suffer a worse fate. The following 15 occupations will experience the biggest decline over the next seven years, losing more than a fifth of all their workers:

15. Hand-grinding and polishing workers

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Median annual wage: $29,550

Projected job growth through 2026: - 20 percent These workers grind, sand and polish a variety of metal, wood, stone, clay, plastic or glass objects using hand tools or hand-held power tools.

14. Coil winders, tapers, and finishers

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Median annual wage: $34,400

Projected job growth through 2026: - 21 percent These workers assist in creating electric and electronic products such as resistors, transformers, generators, and electric motors by winding the wire coils of electrical components. Improved processes, tools, and increased automation are expected to make this manufacturing sector more efficient and, thus, require fewer workers.

13. Postmasters and mail superintendents

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Median annual wage: $75,970

Projected job growth through 2026: - 21 percent These federal workers handle the operational and administrative services of a post office. A combination of automated sorting systems, cluster mailboxes and tight budgets will drastically reduce the number of all postal workers working by 2026, according to the BLS. Add in the fact that more people are opting for electronic bill pay and email to handle tasks that once only went through the mail and the demand for these services isn't what it once was.

12. Data-entry keyers

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Median annual wage: $32,170

Projected job growth through 2026: -21% These workers are responsible for inputting information into electronic or digital systems using data entry devices, such as keyboards or photo composing perforators. They may also need to verify the data entered and prepare materials for printing.

11. Mine shuttle-car operators

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Median annual wage: $56,340

Projected job growth through 2026: -22% These workers operate diesel or electric-powered shuttle cars in underground mines to transport materials from the working face of a mine to mine cars or conveyors.

10. Telephone operators

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Median annual wage: $37,240

Projected job growth through 2026: -23% These workers provide information to customers by consulting alphabetical, geographical or other directories and assist with special billing requests, such as charges to a third party and credits or refunds for incorrectly dialed numbers or bad connections. Some may also handle emergency calls or help children or people with physical disabilities make telephone calls.

9. Computer operators

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Median annual wage: $45,840

Projected job growth through 2026: -23% These tech workers monitor electronic data-processing equipment, respond to operation and error messages and may enter commands at a computer terminal and set controls on computers and peripheral devices.

8. Metal pourers and casters

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Median annual wage: $37,730

Projected job growth through 2026: -23% These workers operate hand-controlled mechanisms to pour and regulate the flow of molten metal into molds to produce castings or ingots. Technological advances in the machinery used in this process will lower demand for human workers, as will the continued competition mental manufacturing industries face from foreign companies for orders from U.S. customers.

7. Foundry mold and core makers

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Median annual wage: $35,430

Projected job growth through 2026: -24% These workers make or form wax or sand cores or molds used in the production of metal castings in foundries. The number of positions is expected to drop because of improvements to and increased usage of labor-saving machinery and the fact that any U.S. manufacturers have moved their production to foreign counties.

6. Motor vehicle electronic-equipment installers and repairers

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Median annual wage: $35,590

Projected job growth through 2026: -26% These workers install and repair the sound, security and navigation equipment used in vehicles. As car companies continue to roll out models with more advanced sound, security, entertainment and navigation systems, these workers receive fewer calls since these higher-quality new systems typically require less maintenance and upkeep than previous models did.

5. Watch repairers

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Median annual wage: $39,910

Projected job growth through 2026: -30% As the name suggests, these workers repair, clean, and adjust timing-keeping instruments, such as watches and clocks. The popularity of smartphones likely diminished people's need for other time tracking devices.

4. Word processors and typists

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Median annual wage: $39,750

Projected job growth through 2026: -33% These office workers type up letters, reports, forms or other material from rough drafts, voice recording, or other documents using either a word processor, computer or typewriter. Some may also perform other clerical duties commonly done by secretaries and other administrative assistants.

3. Parking enforcement workers

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Median annual wage: $39,840

Projected job growth through 2026: -35% These workers patrol an assigned an area, such as a parking lot or city street, and issue tickets or citations to cars parked illegally or cars that have overstayed their parking time limit.

2. Respiratory therapy technicians

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Median annual wage: $51,210

Projected job growth through 2026: -56% These healthcare workers assist respiratory therapists and physicians in caring for patients who have trouble breathing, maybe because of a chronic respiratory diseases such as asthma or emphysema.

1. Locomotive firers

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