This page chronicles the year that "modern" steam locomotive classes first appeared on the Pennsy, starting in 1900.
Going back before 1900, the results are really convoluted and inconsistent due to the PRR's absorption of subsidiary line's locomotives.
Disclaimer: This list may not take into account all rebuilds.
Models in bold are represented in the author's collection.
| Year | Class | Comments |
| 1900 | D16b D16d D16sb E1a G34a |
|
| 1901 | E2 E3 F3 F3b G35s H6a |
|
| 1902 | E21 E2a E3a E7sa F3c F24a G35 G35sa |
|
| 1903 | B6 B6s B8 B23 B29 E2c E7s E22 F3sc F25 H6b |
|
| 1904 | E2b F26 |
|
| 1905 |
E28 |
|
| 1906 | A4 D16sa E2d E3d E23s F27s |
|
| 1907 | G36s G37s H8 H8a H9s H10s K28 |
|
| 1908 | H8b | |
| 1909 | H8sb | |
| 1910 | E5 E6 H8c H34sa K2 K2s K21s |
|
| 1911 | E5s HH1s K2b K2s K2sa K29 L1s |
|
| 1912 | CC1s E6sa H8sc K2a K2s |
|
| 1913 |
B6sa |
|
| 1914 | E6s H9sa K4s |
|
| 1915 | H9sa (rebuilds) | |
| 1916 | A5s B6sb I1sa L1sa |
|
| 1917 | H8sc (rebuilds) H8sa (rebuilds) |
|
| 1918 | B28s I1s N1s |
|
| 1919 | CC2s HC1s L2s N2s N2sa |
|
| 1920 | ||
| 1921 | ||
| 1922 | ||
| 1923 | G5s M1 |
|
| 1924 | ||
| 1925 | C1 | |
| 1926 | ||
| 1927 | ||
| 1928 | A6 | |
| 1929 | K5 | |
| 1930 | M1a M1b (rebuilds) |
|
| 1931 | ||
| 1932 | ||
| 1933 | ||
| 1934 | ||
| 1935 | ||
| 1936 | ||
| 1937 | ||
| 1938 | ||
| 1939 | S1 | |
| 1940 | I1sa (rebuilds) | |
| 1941 | J1 | |
| 1942 | Q1 T1 |
|
| 1943 | HH1 J1a |
Acquired from N&W; built 1919. |
| 1944 | Q2 S2 |
