It depends on the size of the district. Each member decides how many office he/she wants and where. They get something called a representational allowance that varies by member based on factors like how far are they from DC, how large their district is and how expensive it is to set up shop in it. After that, it is up to them to make those decisions based upon where they want to put district offices or how many and how to staff each one. Members will almost always put an office in wherever is their current hometown and in the largest city in their district if those aren't the same place. My member did that, and then did a couple ones spaced in the rural areas (our district was geographically large) to make the farmers feel valued. Within those district offices, there were staff members who concentrated on certain areas of constituent services. For instance, of the 2 full time employees in the largest city office, one's job was to be the exclusive person to work with non-profits and assist them with grant applications, and one managed all the district offices and was the go-to woman for Veterans' issues. The interns were the ones who fielded all the political calls and routed them to the DC office for a response. In the DC office, everyone wore different hats. Like the assistant legislative director, scheduler, and press secretary were all the same person. I was more a utility player--I did whatever needed to be done that hour of that day without question or push back.
