By Jennifer Agiesta, CNN Polling Director

(CNN) -- CNN Poll of Polls averages across 10 key battleground states suggest tight races heading into the final two weeks of the campaign in seven states and former Vice President Joe Biden ahead in the averages of the other three, all of which President Donald Trump won in 2016.

In Pennsylvania, Michigan and Wisconsin, the averages suggest Biden holds the support of a majority of voters and a sizable advantage over Trump.

The Pennsylvania average shows Biden's largest lead. The Democratic nominee averages 52% support to Trump's 43% in polling conducted between September 20 and October 5. In both Wisconsin and Michigan, the averages show Biden with 51% support to 43% for Trump. Trump's victory in each of these states in 2016 came via a margin of less than a percentage point. Except for 2016, all three states broke for the Democratic candidate in each presidential election since 1992.

In 2016, Trump carried all 10 states where CNN Poll of Polls averages are being released Tuesday: Arizona, Florida, Georgia, Iowa, Michigan, North Carolina, Ohio, Pennsylvania, Texas and Wisconsin. He is numerically ahead of Biden in the averages of current polling in just one of these states, Texas, where his support averages 49% to Biden's 45%.

The two candidates are dead even in the Poll of Polls average in Iowa (47% support each) and are nearly even in Georgia (47% Biden to 46% Trump), Ohio (48% Biden to 46% Trump) and North Carolina (48% Biden to 46% Trump).

The averages suggest a narrow tilt in Biden's favor in Arizona and in Florida; 49% support Biden and 45% Trump in both places.

Although it is not possible to assign a margin of sampling error to an average of polls, most of the polls included in these averages have individual margins of error of 4 points or higher. Every poll included in the averages in Pennsylvania, Michigan and Wisconsin finds Biden with a lead larger than the individual margin of sampling error for that poll.

In North Carolina, none of the polls included in the average show either candidate with an edge larger than the individual poll's error margin, including a Washington Post/ABC News poll in the state released Tuesday, which found Biden at 49% support to Trump's 48% among likely voters. Adding that survey to the Poll of Polls average increased Trump's average support there by one point.

In 2016, the averages of high-quality telephone polling conducted at around the same stage in the race across six of these states showed Trump numerically ahead in two (Georgia, 45% Trump to 42% for Hillary Clinton -- the Democratic nominee -- and Iowa, 43% Trump to 38% Clinton), with the candidates tied in Ohio (44% each), and Clinton numerically ahead in Florida (46% to 43%) and North Carolina (46% to 43%). Clinton held a clear advantage in an average of Pennsylvania polls conducted around this time in 2016 (48% to 39%).

But Clinton's average support in each of those states lands below Biden's in the current averages by somewhere between 2 and 9 points, and Clinton's backing did not land above 50% in any of them. Trump's support in 2016 was also a bit below his current averages, but by a range of 1 to 4 points.

The current CNN national Poll of Polls shows Biden with 53% support to Trump's 42%. Although that average is based exclusively on post-debate polling, in none of these states has there been enough high-quality polling to calculate an average based entirely on polls conducted since the first presidential debate in late September.

The averages incorporate polls conducted from mid-September through mid-October, and mostly reflect the views of likely voters in each state. A handful of polls included in the averages in Arizona, Georgia, Iowa, Michigan, North Carolina and Pennsylvania reflect the views of registered voters.

CNN Poll of Polls averages incorporate the most recent polling that meets CNN's standards for reporting conducted in each state. The dates covered and polls included vary by state. Full details for each state's current Poll of Polls average can be found at cnn.com/polls.

This story has been updated with additional polling Tuesday.