The rapid growth of the Lehigh Valley iron industry during the 1850s had resulted in a mining boom,[3] but the heavy ore traffic was highly destructive to local roads.

[9] The railroad also shipped limestone for the furnaces from quarries along the line (one of which it owned), and coal,[10] probably to fuel the stationary steam engines at the mines.

During the summer of 1861, the railroad obtained permission under its amended charter to extend a branch to Siegersville and Orefield.

[11] The right-of-way left the main line near Ormrod, and followed Coplay Creek to around Meyersville Road, then cut cross-country to Siegersville, turning south and descending the hill to Orefield.

[14] On February 1, 1882, all of the Ironton's stock was bought by the Thomas Iron Company, which owned several mines along the right-of-way.

[15] In 1902, the Ironton leased all of the trackage owned by Thomas Iron, including its line from Hokendauqua to West Catasauqua, and performed its plant switching.

The Ironton also built a large yard along the creek in West Catasauqua and a new interchange with the Catasquaua and Fogelsville, by that time controlled and operated by the Reading Company.

Potato farmers became significant shippers on the Siegersville Branch, which also saw deer and buffalo being moved by rail to the Trexler Game Preserve in 1911.

[19] In late 1955, the Siegersville Branch was abandoned, due to increasing truck competition, minimal on-line industry, and the construction of the Northeast Extension across its right-of-way.

[20] In 1996, Whitehall Township purchased 9.2 miles (14.8 km) of the right-of-way from Conrail, transforming it into the Ironton Rail-trail.