The arch could originally have been the entrance arch for the mission's cemetery, but a road has since cut through, separating it from the rest of the cemetery.
St. Ignatius Mission was built in 1891, the cemetery shortly thereafter, so this arch is likely from the early 1890s. It was built with mortar and flat paving stones, some of which have fallen. For the most part, though, it still stands. It stands about nine to ten feet at the top, and likely was never much taller, in spite of deterioration over the years.