Blackburn, claims that Nemethy may have "produced more paintings spanning a wider range of subjects than any other artist in the country." It is estimated that during his life he produced as many as 5,000 paintings.Nemethy is most admired for his highly detailed steamboat paintings along with early American folk art paintings.
He also painted vast landscapes in the style of Albert Bierstadt, along with still lifes, numerous portraits, houses and castles, and historical images.