  Measurements of the midrapidity transverse energy distribution $d{\rm
E}_T/d\eta$ are presented for $p$$+$$p$, $d$$+$Au, and Au$+$Au Collisions at
$\sqrt{s_{_{NN}}}$=62.4--200 GeV. The ${\rm E}_T$ distributions are compared
with the number of participants, $N_{\rm part}$, the number of
constituent-quark participants, $N_{qp}$, and the number of color-strings
(Additive Quark Model-AQM) calculated from a Glauber model. For Au$+$Au,
$\langle d{\rm E}_T/d\eta/(0.5 N_{\rm part})\rangle$ increases with $N_{\rm
part}$, while $\langle d{\rm E}_T/d\eta/N_{qp}\rangle$ is approximately
constant vs. centrality for $\sqrt{s_{_{NN}}} \geq 62.4$ GeV. This indicates
that the two component ansatz, $d{\rm E}_T^{\rm AA}/d\eta=(d{\rm E}_T^{\rm
pp}/d\eta)\ [(1-x)\, N_{\rm part}/2 + x\, N_{\rm coll}]$, which has been used
to represent ${\rm E}_T$ distributions, is simply a proxy for $N_{qp}$, and
that the $N_{\rm coll}$ term does not represent a hard-scattering component in
${\rm E}_T$ distributions. The $d{\rm E}_T/d\eta$ distributions of $d$$+$Au,
and Au$+$Au are calculated from the measured $p$$+$$p$ ${\rm E}_T$ distribution
using two models (AQM and $N_{qp}$) that both reproduce the Au$+$Au data. For
the asymmetric $d$$+$Au system, the $N_{qp}$ model reproduces the data while
the AQM does not.
