McConnell was a very productive illustrator. By his own reckoning, he had done over 800 illustrations from the time he began working professionally in 1899 until 1920, when he made the count referred to as a reply to an inquiry from Gertrude Brinckle about his career as an illustrator.

Most of his work was done for Curtis Publications, particularly for the Saturday Evening Post. During the first decade of this century, the period of his greatest activity as an illustrator, it was not unusual for every other issue to contain three or four of his drawings.

McConnell stoprd working as an illustrator around 1925, because the demand for his work was falling off and also because he disliked dealing with art editors. The latter part of his career was taken up by painting landscapes and by doing some teaching.

The majority of McConnell’s illustrative work has a decorative quality about it, although he was perfectly capable of working in a realistic style and did so when his subject required it.