  A hydrodynamic + cascade model of relativistic heavy ion collisions is
presented and compared to available hadronic data from the SPS to RHIC. The
model consistently reproduces the radial and elliptic flow data for different
particles, collision energies, and impact parameters. Three ingredients are
essential to the success: (a) a reasonable EOS exhibiting the hard and soft
features of the QCD phase transition, (b) thermal hadronization at the phase
boundary, and (c) subsequent hadronic rescattering. Some features of the RHIC
data are readily explained: (i) the observed elliptic flow and its dependence
on $p_{T}$ and mass, (ii) the anomalous $\bar{p}/\pi^{-}$ ratio for $p_{T}
\approx 2.0$ GeV, (iii) the difference in the slope parameters measured by the
STAR and PHENIX collaborations, and (iv) the respectively strong and weak
impact parameter dependence of the $\bar{p}$ and $\phi$ slope parameters. For
an EOS without the hard and soft features of the QCD phase transition, the
broad consistency with the data is lost.
