MIDLAND, Tex. — With oil prices plummeting by more than 50 percent since June, the gleeful mood of recent years has turned glum here in West Texas as the frenzy of shale oil drilling has come to a screeching halt.

Every day, oil companies are decommissioning rigs and announcing layoffs. Small companies that lease equipment have fallen behind in their payments.

In response, businesses and workers are bracing for the worst. A Mexican restaurant has started a Sunday brunch to expand its revenues beyond dinner. A Mercedes dealer, anticipating reduced demand, is prepared to emphasize repairs and sales of used cars. And some well-off oil company managers are cutting back at home, rethinking their vacation plans and cutting the hours of their housemaids and gardeners.

Dexter Allred, the general manager of a local oil field service company, began farming alfalfa hay on the side some years ago in the event that oil prices declined and work dried up. He was taking a cue from his grandfather, Homer Alf Swinson, an oil field mechanic, who opened a coin-operated carwash in 1968 — just in case.