Cost of living tracks with a number of factors, many of which can change rapidly. More stable places often appeal to people on set incomes, or those looking to retire somewhere with a reliable cost of living.
SmartAsset, a financial technology company, conducted a study to find the places where the cost of living is staying the most stable. The Wilmington area ranked among the highest in Delaware. See the top three here:
More information is available here: https://smartasset.com/investing/inflation-calculator#Delaware/CostofLiving