In "Of Mice and Men," a jerkline skinner is a skilled mule driver who operates a team of mules. This job requires expertise in handling mules, which can be stubborn and difficult to control. The term "jerkline" refers to the main line that connects the lead mule to the driver, and the jerkline skinner is responsible for guiding the team and controlling the mules with the use of this line.
Steinbeck uses the character Slim, who is a jerkline skinner, to illustrate the importance of this job and the respect it commands among the other workers on the ranch. Slim is portrayed as a skilled and respected worker who is able to handle the mules with ease and is admired for his expertise. When George and Lennie arrive at the ranch, Slim is the first person they meet, and he immediately impresses them with his ability to handle the mules.
In Chapter 4, when Curley's wife accuses Slim of being the only one who understands the loneliness of ranch life, she says, "I think Slim's a jerkline skinner. [...] He's the prince of the ranch." This statement emphasizes the high regard that Slim is held in by the other workers, and his expertise as a jerkline skinner is seen as a key factor in his respected position on the ranch.
Overall, the jerkline skinner is a significant character in "Of Mice and Men," representing the importance of specialized skills and the respect that comes with expertise in a particular job. Steinbeck's portrayal of Slim as a skilled and respected jerkline skinner adds depth to the novel's exploration of the working-class culture during the Great Depression.