When candidates are collecting dollars, it is easier to go to a relatively small number of wealthy donors who can write $2,000 checks than to gather many, many more small contributions from a large number of people. Candidates with many small donations likely reached out to a more economically and socially diverse group of citizens.

Federal election law does not require itemized reporting of donations of $200 or less. Members of Congress who receive more money from small donors, especially in proportion to their overall contributions, probably are turning more to their whole constituencies to raise money instead of to a few well-heeled supporters.