Recent closures of several big-box stores are leaving ample space empty nationwide. : The amount of retail space turning vacant in 2018 is on pace to break a record, reports the CoStar Group, a commercial real estate services firm that has been tracking the amount of retail square footage slated to close nationwide since 2008. Factoring up to April so far of this year, more than 90 million square feet of retail space is expected to go empty.