Editing Template:LocoType/Atlantic

<!-- Template:LocoType/Atlantic -->
<!-- Sourcing tier: Broad/categorical. Prototype history and established industry consensus acceptable without Tier 1 confirmation. -->
<!-- Stack: Prototype. Steam. Generic type — covers the 4-4-2 wheel arrangement as a locomotive class rather than any specific railroad's class. -->
<!-- Wheel arrangement: 4-4-2 -->
<!-- Prototype manufacturer: Various -->
<!-- Era: 1895–1930s -->
<!-- Last updated: [DATE] -->

The 4-4-2 Atlantic was the first American locomotive type specifically designed for high-speed passenger service — a configuration that added a single trailing axle to the established four-coupled arrangement to allow a larger firebox and the sustained steam generation that fast express trains demanded. Introduced in the late 1890s at a moment when American railroads were pushing aggressively for faster passenger schedules, the Atlantic represented a genuine engineering advance over the ten-wheelers and Americans that had been handling passenger duties: its expanded firebox could produce more steam, its four-wheel leading truck provided stable guidance at higher speeds, and its driving wheel diameter was typically larger than freight types, optimizing it for speed over tractive effort. The type spread quickly across the eastern and midwestern railroads that competed most intensely for passenger traffic, and for roughly a decade it was the premier American passenger locomotive.

The Atlantic's reign at the top was brief. As passenger train weights increased through the 1900s and 1910s — heavier cars, dining cars, sleeping cars, and longer consists — the four-coupled arrangement's limited tractive effort struggled to maintain schedules with heavier loads, and the more powerful six-coupled [[4-6-2|Pacific began to displace it from premier service. Individual roads developed no]]table Atlantic classes that extended the type's useful life — the [[Pennsylvania Railroad|Pennsylvania Railroad]]'s E6s and the [[Milwaukee Road|Milwaukee Road]]'s high-speed Atlantics among them — but by the 1920s the type had largely retreated to lighter trains and secondary service. In O Gauge, the Atlantic appears as a passenger locomotive subject for the pre-World War I era, representing the brief moment when the four-coupled type was the fastest thing on American rails.