Newcastle University Library in the United Kingdom has what is believed to be the first photographs of Niagara Falls in their Special Collections, from around 1840. The images are daguerreotypes (one of the earliest types of photographs) and were taken by H. L. Pattinson. There are many images in the collection. If you start at this page, you will read a bit about the discovery of the images. Then if you click The Images link on the left, you’ll see a thumbnail of all the images. From there you can view the Niagara Falls pictures.
images copyright © Newcastle University Library (1997)