The federal Senate is 2 Senators per state, no voting representation for territories (places not in admitted states) or Washington DC. So Vermont and Wyoming, with populations around 600,000 each, have the same vote strength as California (39M) and Texas (31M) -- 1.2 million people equated to 70 million.
Gerrymandering ("from Gerry's salamander-shaped district") is the practice of the ruling party in any state drawing their districts for the federal House of Representatives so that their party wins multiple districts (by, say, 52-48%) and making the other party win a smaller number of districts (by 90-10%). Each district is required to have roughly the same number of people in it. The shaping is bad, but the per-population equality of representation is nearly optimal.
Academics generally conclude that of the 435 districts, no more than 40 or 50 are actually representative of the political demographics of the state as a whole.