In the United States government, we have two Houses in the Legislative branch. These two Houses are the House of Representatives and the Congress. By definition, Congress has only two members per state (so, 100 members). The House of Representatives has the number of members based on the population of the states they represent. I think they have around 500 members, but don't quote me on that.
So, if I understand what you're asking, the Congress is the house with the least members.
I hope that helps.
U.S. SENATE,ONLY 100 MEMBERS