This has a largely Appalachian range, but with some reported disjunct outliers (K); see also notes under insperata, which has been confused. C.porteri sensu stricto occurs mostly in or near the Alleghenies and Blue Ridge, from N.Y. to Ala., and it is especially common in the Ridge & Valley region of Va. and W.Va. (NS: CEGL 8516). C. porteri occurs mostly in thin rocky subxeric woods (often with Quercus montana, Q. stellata or Pinus virginiana) on relatively gentle upper slopes and ridges with non-calcareous soils, usually as dense clonal stands. Flowering in Ky. Is rare, but has been observed along power-line rights-of-way in ROWA (colls. of A. Risk for MDKY; Campbell et al. 1992), where initially misidentified as ssp. Insperata. The report by Pr from WARR (K) is dubious; no coll. has been located and "Calamagrostis porteri" is crossed out by hand in the author's copy (archived in library at MO). Occurrence has been verified in BULL, where M. Homoya discovered a few patches on siltstone; relocated by T. Littlefield (NP) in 2015, this population had virtually disappeared perhaps due to lack of fire and excessive browsing by deer.