  Given a graph $G$, the (graph theory) general position problem is to find the
maximum number of vertices such that no three vertices lie on a common
geodesic. This graph invariant is called the general position number (gp-number
for short) of $G$ and denoted by ${\rm gp}(G)$. In this paper, the gp-number is
determined for a large class of subgraphs of the infinite grid graph and for
the infinite diagonal grid. To derive these results, we introduce
monotone-geodesic labeling and prove a Monotone Geodesic Lemma that is in turn
developed using the Erd\"os-Szekeres theorem on monotone sequences. The
gp-number of the 3-dim infinite grid is bounded. Using isometric path covers,
the gp-number is also determined for Bene\v{s} networks.
