the market value of slaves in the Louisiana Territories--a concern of sugar growers in the 1820's.
the Florida Everglades
the US candy industry
the artificial sweeteners industry
the market for US corn (source of both fructose and ethanol)
European Union sugar policies
small sugar-producing nations such as Belize and the Dominican Republic that received US food aid as compensation for being denied access to the US sugar market.
other sugar producers such as Colombia and Peru (what alternative crop do they export to us instead?)