Natural gas is almost 50% more expensive per therm in the Northeastern United States than it is in the rest of the country, and fuel costs matter in these states, which have cold winters, so it isn't surprising that 82% of the heating oil consumed in the United States is used there.
But, if you compare natural gas heating and heating oil, strictly based on fuel costs, it has been cheaper to heat with natural gas than with heating oil in the Northeast every year from 2005 to 2010 in the Northeast.
If the trend persists, homeowners will convert from heating oil to natural gas, and one of the main non-transportation sector sources of oil demand will greatly decline. One notable consequence of this shift would be to decouple heating costs for average Northeasterners from the global oil markets, which they currently track closely, in turn, linking the entire national economy more strongly to world oil markets. It should also reduce air pollution, and dent the trade deficit, about half of which is attributable to oil imports, with relatively little economic pain.