Establishing the value attached to ecosystem services provides instrumental information in the planning of conservation initiatives to ensure forest ecosystem sustainability. This study fills a gap in the literature regarding the value associated with ecosystem services for which their direct use can be challenged by distance and geo-political boundaries. We estimated US residents' willingness-to-pay (WTP) for the restoration of degraded temperate out-of-state and tropical out-of-the-country forested watersheds for improved water quality services under hypothetical payment for ecosystem services (PES) programs. Factors influencing WTP were estimated using a bivariate probit model and mean WTP values adjusted for self-reported certainty of responses. Transboundary economic value decay was reflected on lower households' annual WTP values for the restoration of the tropical out-of-the-country (US$ 124.15–238.30) than temperate out-of-state (US$ 131.70–256.79) forested watershed ecosystems. Bequest and existence were the non-use value motivations most strongly associated with WTP for temperate out-of-state and tropical international PES programs, respectively. Other salient explanatory variables included program cost to households, age, sex, income, household size, political party identification, attitudes towards PES, affiliation with environmental conservation group and direct experience with comparable natural resources. This study offers evidence of positive prospects for transboundary PES programs to restore geographically delimited ecosystem services driven by existence, option and bequest value motivations.