A quick Google search revealed little biographical information about him, though this site is fairly useful.
Besides working in many media, Horter used a variety of styles over the years, as can be seen in the images below. So even though he was very competent, his work is not distinctly "his" due to all that variety. That said, it should be noted that his subject matter was largely architectural or townscapes. Almost no images featuring people could be found on the Internet.
Packard poster from around 1914. The setting is Paris' Avenue de l'Opéra constricted to suit the dimensions of the poster.
New York's Woolworth Building Under Construction, c. 1912.
Traymore Hotel, Atlantic City, c. 1915.
Two scenes of Toledo, Spain from about 1924. Here we see a touch of Cubist influence.
Ditto for this Delaware River Scene.
Chrysler Building Under Construction - c.1931.
City scene, also a whiff of Cubism.
Gloucester, Massachusetts scene, 1932. Here a touch of modernist simplification, common at the time.
The Old Barn, 1939. A conventional watercolor, but limited colors.
Still Life, also from 1939, but in a Cubist style.