Here's an interesting tidbit about the Boston City Charter. If one of the four at-large city councilors were to leave his or her position, the candidate who finished fifth in the election, if willing and eligible, would become the fourth at-large city councilor.
What does that mean? Let's say, hypothetically, At-Large City Councilor Ayanna Pressley were to become a US congresswoman and vacate her city councilor seat. Under those circumstances, current At-Large City Councilor Stephen Murphy -- who just lost his seat -- could rejoin the council, provided it happened in the next two years.
This procedure for how an at-large city councilor vacancy is filled is dictated by Boston's City Charter in Section 15.
But wait, there's more. Because there wasn't a sixth at-large candidate in this election, if Murphy weren't eligible -- if he were no longer living in Boston, for example, or if didn't want to be back on the council -- the sitting Boston city councilors would have 15 days to choose a Boston resident to fill the at-large position. If they didn't, then the mayor would select an at-large city councilor to fill the position.
It's a different scenario if a district city councilor vacates his or her position. In those cases, positions are filled by special elections. For example, take current District 6 City Councilor Matt O'Malley, who won his seat in 2010 in a special election after John Tobin vacated the position to take a job at Northeastern University.
Interestingly, on Wednesday, current District 3 City Councilor Frank Baker filed a home rule petition that would change the process to fill at-large city councilor vacancies. His proposal would create a special election to fill the vacancy. The matter is currently in the Government Operations Committee and would need the approval the Boston City Council, mayor and state legislature.