  We show that the locations where finite- and infinite-time clustering occurs
for the 1D Euler-alignment system can be determined using only the initial
data. Our present work provides the first results on the structure of the
finite-time singularity set and asymptotic clusters associated to a weak
solution. In many cases, the eventual size of the cluster can be read off
directly from the flux associated to a scalar balance law formulation of the
system.
