Man, we have a lot of smart railroaders here! The "coast to coast" tenders didn't literally go from the Atlantic to the Pacific, but they doubled the distance a train could travel without refueling. The Pennsylvania Railroad often used them to move trains quickly over the Appalachian Mountains of the eastern US.
This specific coast to coast tender 
is the tender for the Pennsylvania Railroad's controversial T1 steam locomotive.
The PRR built 52 of these monsters, none or which lasted more than 10 years. Designed to easily run at 100mph, they were often run faster, causing excessive wear. Their excessive maintenance costs doomed them.
Defenders point out that if the PRR had used them properly, they would have remained as some of the greatest locomotives ever built. However, even if held down to 100 mph, engineers had a hard time controlling the excess power, which produced wheel slippage.
The tenders were sometimes used for other large steam locomotives.
