  An $r$-identifying code on a graph $G$ is a set $C\subset V(G)$ such that for
every vertex in $V(G)$, the intersection of the radius-$r$ closed neighborhood
with $C$ is nonempty and unique. On a finite graph, the density of a code is
$|C|/|V(G)|$, which naturally extends to a definition of density in certain
infinite graphs which are locally finite. We present new lower bounds for
densities of codes for some small values of $r$ in both the square and
hexagonal grids.
