The number of rigs actively exploring for or producing oil and gas in North Dakota, is down more than half from its historic peak, state data show Monday.

State data show 93 rigs in active service in North Dakota, a state at the heart of the shale boom in the United States. That's one of the lowest rig counts in years, marking a 50 percent decline year-on-year and a 55 percent from the historic peak reached in 2012.

The low price of oil, down about half from its June 2014 peak for the U.S. benchmark, has forced energy companies to spend less on exploration and production. Oil services company Baker Hughes last week reported 988 active rigs in the United States for the week ending April 10, down nearly 4 percent from the previous week and 46 percent lower year-on-year.

Baker Hughes itself is in the early stages of a takeover from rival Halliburton as both companies struggle to maintain the status quo in the era of low oil prices.

In a mid-March report, North Dakota said the low price of oil was "by far the biggest driver behind the slow-down" in the Bakken shale reserve.

The lower rig count in North Dakota, meanwhile, has translated to a slowdown in oil production.

More than 90 percent of the state's oil production comes from Bakken shale. In January, oil production was 1.19 million barrels per day, a 3 percent decline from the previous month. The state's all-time high was around 2 million bpd, reached late last year. Data from February is expected from North Dakota later this week, though a federal report on oil production nation-wide predicts the slump will last at least through the summer.