The original name of 30th Street was Smith Street. Bruce S. Cridlebaugh says that the street was named for an S. Smith, who owned property at the intersection of this street with Penn Avenue; Smith’s lots appear in the 1872 Hopkins atlas.[1, 2]
In 1868, Pittsburgh’s modern sequence of numbered streets was created by renaming all the streets perpendicular to the Allegheny River; Smith Street became 30th Street.[2, 3, 4]
Atlas of the cities of Pittsburgh, Allegheny, and the adjoining boroughs. G. M. Hopkins & Co., Philadelphia, 1872. http://historicpittsburgh.org/maps-hopkins/1872-atlas-pittsburgh-allegheny; 1872 layer at http://esriurl.com/pittsburgh.
Cridlebaugh, Bruce S. “Field notes: Changing Pittsburgh street names—from downtown to Lawrenceville.” Pghbridges.com: Bridges & tunnels of Allegheny County & Pittsburgh, PA, Feb. 9, 2000. http://pghbridges.com/articles/fieldnote_pghstnames.htm.
Killikelly, Sarah H. The History of Pittsburgh: Its rise and progress. B. C. & Gordon Montgomery Co., Pittsburgh, 1906, p. 534. DonsList.net HistPgh1909M; Google Books kXmloex-vr8C, poRU0YjqrzsC; HathiTrust 100122020; Historic Pittsburgh 00adc8925m; Internet Archive historyofpittsbu00kill, historypittsbur00killgoog.
“An ordinance changing the names of streets.” Pittsburgh city ordinance, 1868. Passed Aug. 31, 1868. Reprinted in the Pittsburgh Gazette, Sept. 2, 1868, p. 5 (Newspapers.com 86347563), Sept. 3, p. 3 (Newspapers.com 86347623), and Sept. 4, p. 3 (Newspapers.com 86347714).