  This paper proposes a stylized, dynamic model to address the issue of sorting
online. There are two large homogeneous groups of individuals. Everyone must
choose between two online platforms, one of which has superior amenities (akin
to having superior local public goods). Each individual enjoys interacting
online with those from their own group but dislikes being on the same platform
as those in the other group. Unlike a Tiebout model of residential sorting,
both platforms have unlimited capacity so there are no constraints on
cross-platform migration. It is clear how each group would like to sort
themselves but, in the presence of the other type, only the two segregated
outcomes are guaranteed to be equilibria. Integration on a platform can be
supported in equilibrium as long as the platform is sufficiently desirable. If
online integration of the two communities is a desired social outcome then the
optimal policy is clear: make the preferred platform even more desirable.
Revitalizing the inferior platform will never lead to integration and even
increases the likelihood the segregation. Finally, integration is more elastic
in response to an increase in platform amenities than to reductions in
intolerance.
