By now, we know the Senate results well: The Democrats picked up seats, including victories in Indiana and Missouri that few expected at the beginning of the cycle. Of the 10 seats that the Cook Political Report listed as toss up races two months before the election, Democrats won nine, losing only in Nevada.

But boy did it cost a lot.

In those ten toss-up races, $412.9 million was spent by candidates and outside groups, an average of $41.3 million per race. It was remarkably close. On average, Republican total spending per race was $21.1 million, Democrats $20.2 million. Without Connecticut, where Republican candidate Linda McMahon, a self-financed candidate, spend $36 million, Democratic spending was $21.3 million on average, and Republican spending was $18.6 million on average.

In just candidate spending, Democratic candidates spent $108.6 million. Republicans spent $114.2 million, though 31.5% of that was from McMahon. In the other nine races, Democratic candidate spending was $100.0 million; Republican candidate spending was $78.2 million. (Candidate spending totals are only through October 17, the most recent data available through the FEC)

When we add in outside spending, seven races broke the $40 million mark, including a $78.6 million race in Virginia.

Here are the top seven:

By comparison, last election, six races broke the $40 million mark, with Florida topping out at $68.4 million.

In seven of the ten Cook toss-up seats, the Democratic candidate raised more money than the Republican, though, again, one of those was Connecticut. Democrats also were behind in candidate fundraising in Indiana and North Dakota.

Republicans did have an outside money advantage in eight of the ten races (Virginia and Montana being the exceptions). But it didn’t seem to matter.

For full data on competitive Senate seats, click here.

It’s unclear whether Democrats’ general success in the Senate benefited from their strong fundraising or a general shift towards Democrats. Regardless of whether or not the extra money mattered, nobody appears to have wanted to risk the possibility that it didn’t. Many of these races looked like arms races, with neither side willing to back down. For a more detailed analysis of the effect of money, see our analysis of House races.

The lingering result will likely be that we now have a new standard in what it takes to run for the Senate. $78.6 million for the most competitive Senate race. And $41 million to win a Senate race in a state with a population of just under one million people. That’s $41 spent per person in the state of Montana.

What this signals to every sitting Senator who might potentially face a close race is this: Start raising money now, and make sure that you don’t upset any potential contributors. It doesn’t look like either side has any plans to back down.