In a conversation lat week, the number of empty lots in Carbondale came up and the person I was discussing this with pointed out a major reason for the number of empty properties: pricing.
A large number of these empty lots are owned by people who do not live in Carbondale. They have either moved away or inherited them from relatives. The property is paid for, so aside from maintenance and property taxes, they have no costs associated with them. The owners can therefore sit on them, waiting to sell to someone willing to meet their price, and in most cases, that price is way too high for a prospective purchaser.
According to the person I spoke with, who is in a position to know, owners are asking $10,000 to $15,000 for lots the city estimates a value of $1500 to $2000. Demanding a price premium of 10 times the estimated value of your property is not going to entice any buyers, but since the owner has only minimal costs associated with it, there's no incentive for them to reduce the price.