This is Pennsylvania Railroad 3768, a K4-class locomotive that was rebuilt with a custom streamlined covering designed by Raymond Loewy. It was perhaps most famously showcased alongside B&O's William Mason and the Best Friend of Charleston at the 1939 World's Fair.

References (Locomotive)

https://pbs.twimg.com/media/DWwoejhWsAAXaFa.jpg:large

https://64.media.tumblr.com/8843aaa624352b0d09372ba30b06c004/016f34b25012a34a-e7/s1280x1920/95614a25c723d8ba3e5f0a11797353ec135ac512.jpg

https://64.media.tumblr.com/5c78da0460256da6f09a2037c50112b4/016f34b25012a34a-3a/s1280x1920/774697d7eaab6eda2adce899d2d4cca16bd06a5e.jpg

https://64.media.tumblr.com/4fb607da086661d5b00813305d819ac0/016f34b25012a34a-6a/s2048x3072/941a1ae20acecd2d23e55fb66298ec5e95adafb9.jpg

Coaches

https://www.youtube.com/watch?v=kY83v3-z2YE

https://www.american-rails.com/images/PRR_FOM.jpg

https://jbritton.pennsyrr.com/images/Trail-Blazer-Jeff-4-9-16A-top.jpg

https://c8.alamy.com/comp/MKRF3X/pennsylvania-railroads-south-wind-train-MKRF3X.jpg

http://www.trainweb.org/fredatsf/bwy49kato.htm