For the 2007 Cambridge elections, everyone knew there would be a big drop. One contributing factor was that two long-time major vote-getters, Anthony Galluccio and Michael Sullivan, had been elected to other offices and were out of the running. Normally this draws out new candidates who bring out new voters, but the timing of the departures was late enough that few new, credible candidates emerged. Open seats usually bring greater turnout, but not this time. The lack of any significant issues also led to a decline in turnout.
Voter turnout in municipal elections and primary elections has plummeted in many places in Massachusetts in recent years. The drop in Cambridge wasn't nearly as bad as the drop in Boston, and cities like Worcester saw drops that were well below even the most pessimistic predictions. This can be explained by the fact that people are likely not to see as much relevance in local elections now, especially now that rent control has gone and access to City jobs is less of an issue as higher-income people buy up condominiums in Cambridge. Voter turnout generally rises when the stakes are higher and they were a lot lower in 2005. How the current economic situation influences voter turnout is yet to be seen.