Firstly I don't know the proper term, but what I mean is that there are 2 senators for each US state, and they serve 6 year terms, and 1/3 of the senate is up for grabs each election cycle. I'm referring to what 3rd of the Senate was it decided a state's Senators would serve in.
I was in my Poli Sci class today and the professor said that in the first senate it was a luck of the draw thing on wether you serve 2, 4, or 6 years (in the original senate), then it reverted to the constitutional 6 year term. Was a similar thing used for new states? How was it decided which 3rd a Senator was in for a new state?
The term is "classes", directly from the US Constitution, article I, section 3:
Immediately after they shall be assembled in Consequence of the first Election, they shall be divided as equally as may be into three Classes. The Seats of the Senators of the first Class shall be vacated at the Expiration of the second Year, of the second Class at the Expiration of the fourth Year, and of the third Class at the Expiration of the sixth Year, so that one third may be chosen every second Year
As for the process of class assignments, I can think of few places as concise and authoritative as the US Senate FAQ:
The process of assigning the first senators to the three separate classes was quite informal. In the first Senate, on May 15, 1789, the total body was divided into three groups, being sure that no state had both senators in a single group, and then lots were drawn for class one (expired in two years), class two (expired in four years), and class three (served the full six-year term), and the process moved on from there.
When new states are added, the number in each group is kept as even as possible, and then a coin is tossed to see which class the new senators will enter. For example, there is currently one class with 34 members and two classes with 33 members each. If a new state should be added to the Union, the two senators would be assigned to the two classes with only 33 members, making all three classes even at 34. Then the two new senators draw lots to see which class they join.
Except I don't know how to understand "coin is tossed" versus "draw lots"; I saw a hearsay reference saying that, at least for Hawaii, lots were drawn.