When Blackton was founded in 1954 in Orlando, no one could have predicted that the mom-and-pop building-supply business in what was then a sleepy citrus town would survive so long and become a bellwether for central Florida’s economy. The family-owned company, which today is still run by Blackton family members and employs 63, is signaling growth ahead: $20 million in new contracts for flooring and roofing for more than 2,000 homes ordered by seven builders in projects from Daytona Beach and Orlando to Tampa and Clearwater.