Experiments were performed to ascertain the single-phase heat transfer enhancement provided by streamwise curvature. Curved and straight rectangular flow channels were fabricated with identical 5.0 x 2.5 mm cross-sections and 101.6 mm healed lengths in which heat was applied to a 32.3 min radius concave wall in the curved channel and a side wall in the straight. Reynolds number ranged from 9000 to 130 000 and centripetal acceleration for the curved how reached 315 times the earth＇s gravitational acceleration Nusselt numbers defined with hydraulic and thermal diameters were consistently underpredicted by previous correlations developed for full-periphery-heated channels but were accurately predicted when defined with heated width. Convection coefficients were enhanced due to how curvature for all conditions tested, and detailed experimental correlations are provided for both the straight and curved configurations. Increasing Reynolds number produced different enhancement trends for different locations along the heated wall, decreasing the enhancement near the inlet and increasing it elsewhere downstream Mechanisms responsible for the curvature enhancement are believed to be Dean vortices and a shift in the maximum axial velocity toward the concave wall. These mechanisms require a finite distance to develop sufficient strength to influence heat transfer, which explains the different enhancement trends observed for different locations along the heated wall.