  Statistical physicists have become interested in models of collective social
behavior such as opinion formation, where individuals change their inherently
preferred opinion if their friends disagree. Real preferences often depend on
regional cultural differences, which we model here as a spatial gradient $g$ in
the initial opinion. The gradient does not only add reality to the model. It
can also reveal that opinion clusters in two dimensions are typically in the
standard (i.e.\ independent) percolation universality class, thus settling a
recent controversy about a non-consensus model. However, using analytical and
numerical tools, we also present a model where the width of the transition
between opinions scales $\propto g^{-1/4}$, not $\propto g^{-4/7}$ as in
independent percolation, and the cluster size distribution is consistent with
first-order percolation.
