Utility Workers Union of America
AFL - CIO Local 127

There is no set rule for how many stewards you’ll find in a particular workplace, or how many will have responsibility for particular work areas.  Sometimes there is a natural organization of the workplace—such as a well-defined work area, or a particular work shift or one building separated from the rest of a larger facility—so that it makes sense for stewards to be assigned on that basis.  So it may be that stewards where you work function according to workplace geography—a steward may be responsible for all union members on a particular floor of a building, for example.  Maybe your steward is one who handles matters that directly affect everyone who does your type of job—such as all accountants in a particular government agency, or all nurses aides on a particular wing of a nursing home—or maybe your steward deals with everyone who works on your shift.
—Adapted from The Union Member's Complete Guide, by Michael Mauer