B.C. elections tend to be close. Over the last 40 years, only two have been decided by more than 10 percentage points. Only one has been decided by more than 10.1 points.

That's worth bearing in mind as the election polls tighten. The latest poll, from Ipsos, suggests the New Democratic Party leads the BC Liberals by 10 points. The day before that, an Angus Reid poll suggested the NDP leads by seven points.

It's a long way to election day, but a 10-point victory would be the third-largest margin of the last 40 years. A seven-point victory would be the fourth-largest in that period.

During the 1960s, W.A.C. Bennett's Social Credit party beat the NDP three times by a margin of 12 to 13 points. But since the W.A.C. era ended in 1972 with an eight-point victory by the NDP, things have been much tighter.

Here are the results of the nine elections of the last four decades. The table shows the winner's margin of victory in percentage points as well as the percentage of seats in the legislature the winner took.

Election	Winner	Margin	Seat Percentage
1975	Social Credit	10.09	64
1979	Social Credit	2.24	54
1983	Social Credit	4.82	61
1986	Social Credit	6.72	68
1991	NDP	7.46	68
1996	NDP	-2.37	52
2001	Liberal	36.06	97
2005	Liberal	4.28	58
2009	Liberal	3.67	58

The median margin of victory for this period is 4.82 percentage points.

The biggest victory by far was 36 points in the New Democrat wipeout of 2001, when voters went to the polls with pitchforks and torches looking to throw the bums out even unto the seventh generation. The narrowest victory was in 1996, when the NDP won with fewer votes than the Liberals. That wasn't the first time in B.C. history that the party with the most votes lost. In 1952, the Co-operative Commonwealth Federation beat Social Credit by four points on the final count, but took one less seat.

As that suggests, in our first-past-the-post system you don't need to run up a big lead to win control of the legislature. The NDP took more seats in 1996 because their vote was spread more evenly over the province's ridings, while the Liberal vote tended to cluster in places like West Vancouver and the Fraser Valley.

As the table above also shows, the size of a party's victory doesn't translate directly into seats in the legislature. It all depends on where a party's votes are located and the strength of third parties.

The two charts below give a graphic illustration of just how close B.C. elections tend to be. If things get tight on May 14, it won't be anything out of the ordinary.

Find Tyee election reporting team member and contributing editor Tom Barrett's previous Tyee articles here. Find him on Twitter or email him.