U.S. patent granted for railway-crossing gate

On January 21, 1890, Mary Isabelle Riggin’s invention of a railway-crossing gate was formally issued U.S. Patent No. 419,612, recognizing her as the patent holder for an early automated crossing device.¹ The patent described a mechanical system that connected the movement of a train to the raising and lowering of a barrier at road crossings, providing a clear, physical warning to roadway users that a train was approaching.

This official grant came at a moment when the U.S. rail network was still expanding, and grade-crossing accidents were a major public concern.² By securing legal protection for her design, Riggin helped legitimize the concept that such crossings should be engineered systems, not ad hoc arrangements or the exclusive domain of human flagmen. Her work offered a technical pathway for railroads and municipalities seeking ways to reduce collisions at intersections where trains intersected with everyday traffic.

As a woman inventor in the late nineteenth century—a period in which women’s names appeared only rarely on mechanical patents—Riggin’s patent grant was itself barrier-breaking. Her success demonstrated that women could not only identify safety problems in emerging technologies but also design, document, and legally protect complex mechanical solutions. Over the decades, more advanced electrically controlled and fully automated gates would evolve from this basic principle of a controlled, coordinated barrier at rail crossings.¹² Riggin’s 1890 patent thus marks an early and influential moment in the history of railroad safety engineering and women’s contributions to that field.