As an historian of American technology (and other areas including the 19th Century US, as well as women and gender), I've often been frustrated (though perhaps not surprised) by the relative paucity of the presence of women as individuals in this sub-field's historical literature. Of course, from before the arrival of Europeans American women have worked in agricultural fields, often beside men, and using various implements of technology while doing so. Women also appear prominently in accounts of Lowell's textile mills, and in the form of laborers in a number of industries employing technology, especially at times of war (the women in Civil War munitions factories and so famously represented by Rosie the Riveter in WWII are merely the most well known).
Yet, since my class is organized around the inventions (and reinventions) of twenty or so key artifacts of American technology, I've all too often talked about women's roles in technology as secondary or reactive, especially before 1900. The number of prominent inventions women had direct roles in creating before the 20th century is harder to highlight given the roles that women were expected to play, and the restrictions often placed on their educations and their actions.
Still, there are three women of the "long 19th Century" that I want to mention, women who were involved in some of the most significant acts of technological creation of their day and place.
- Catherine Green was a widow and Georgia plantation owner who certainly encouraged Eli Whitney to work on the problem of removing seeds from cotton. What's less clear historically speaking is how much of a role she played in helping Whitney discover what may have been the key aspect of that the cotton gin, the wire teeth that pulled the cotton fibers from those pesky seeds. 
- Emily Warren Roebling was the spouse of Brooklyn Bridge head engineer Washington Roebling. When he was struck down and crippled by "caissons disease" after spending too much time in the pressurized diggings below the surface of the East River it was Emily Roebling who took over as the main contact between Washington and the bridge effort. For years while Washington apparently watched from the window of a nearby building, Emily was his eyes and ears, learning a great deal of engineering on what was the largest bridge in the world at the time. When it was completed, it was Emily Roebling who made the first official crossing of the bridge in 1883. [1869-1883]
- Finally, Amanda Jones is the least well known of the three, though I'd argue fairly important. Though women were often chiefly responsible for preserving food in their households in the 19th Century, most of the innovations in commercial preservation came from men like Gail Borden, H. J. Heinz, and John Torrence (of Campbell's Soup). In 1872, however, Amanda Jones was the inventor of a vacuum-based process for canning foods that made them last longer and taste better.
Happy Ada Lovelace Day!