Staple Bend Tunnel was the first railroad tunnel in the United States, built in 1832 by the Allegheny Portage Railroad. The tunnel is 900 feet long, and cost $37,500 in 1832 dollars.

The Allegheny Portage Railroad was a briefly-important cog in the US transportation network. A system of canals, railroads, and inclined planes, of which the Allegheny Portage was a part, connecting Philadelphia and Pittsburgh, was completed in 1834. The system proved to be inefficient, slow, prohibitively expensive to maintain, and dangerous. The Portage Railroad, which simply climbed over the Allegheny Mountains, was the worst offender. It was comprised of ten separate inclined planes, connected by rail.

Staple Bend Tunnel is located approximately five miles east of Johnstown, Pennsylvania, at a location known as Mineral Point. The portage railroad ran only as far as Johnstown, to the west, and Hollidaysburg to the east.

It took until 1854 for an all-rail route to be built between Philadelphia and Pittsburgh, by the Pennsylvania Railroad. The PRR reached Johnstown in 1851, and struck the death blow for the Allegheny Portage Railroad. The PRR immediately captured the lion's share of the east-west traffic. The backers of the Portage RR quickly moved to build their own all-rail route between Johnstown and Hollidaysburg, and upon its completion in 1855, abandoned the inclined planes and Staple Bend Tunnel.

The New Portage RR was unable to compete with the PRR, and in 1857, the PRR bought the right-of-way of both portage railroads. In 1903, the PRR reopened the New Portage RR, when the volume of traffic became too great for its own line, and it wasn't abandoned for good until 1981. The "old" Portage RR, including Staple Bend Tunnel, was of no strategic importance, and Staple Bend was eventually sold to the Bethlehem Steel Company, who sealed up the tunnel and laid a water pipeline through it.

The tunnel eventually fell into the hands of the National Parks Service, and was re-opened in 2001 as part of a historic walking trail. The tunnel was thus opened to the public for the first time in almost 150 years.