On March 10, Maine held a special election to fill the vacancy in the State House, district 93. The vote was: Democrat Anne Beebe-Center 52.89%; Republican James Kalloch 44.51%; Green Ronald Huber 1.97%; Libertarian Shawn Levasseur .64%. See this story.
When this same seat had been up in November 2014, the vote had been: Democratic 52.01%; Republican 47.99%. The Republican nominee had run in November 2014 as well as in the recent special election. Because this district had one of the closest votes in November 2014, there was considerable suspense as to who would win the special election. That probably kept the minor party vote lower than it would have been otherwise.
UPDATE: this article explains the unusually high spending by the major parties in this race, and why the stakes for them were so high.