As such, construction on the extension from Peapack to Mendham, New Jersey started on August 26, 1890 under the Rockaway Valley Mendham Extension Railroad Company, although the company wouldn't be legally incorporated for another 3 weeks. The first train to Mendham ran on June 25, 1891. Engineering-wise the section to Mendham, which also passed through the town of Ralston, New Jersey, was relatively unremarkable by RVRR standards, although the 1.8% grade northward to Mendham would have been significant for many other railroads.