Average first year resident salary is mid $30Ks; some places where cost of living is higher (like NYC), some salaries are higher (up to low $40Ks). After you are licensed (usually after internship), you are eligible to moonlight if your program allows it. Moonlighting is usually 1 8-12 hr shift, usually in the ER or in an after hours clinic. They make about $50/hr and usually include malpractice insurance. Competition for moonlighting positions is more intense in cities where there are a lot of fellowships (post residency) training docs as they are more desireable than residents.
Some residencies where pay is relatively low have built in moonlighting to increase resident income.
Hope this helps, Ana 🙂