Updated at 5:06 p.m. ET

With both President Trump and Democratic presidential nominee Joe Biden still short of the 270 electoral votes needed to claim victory, anxious Americans are left with little to do but be patient and wait as election officials in key swing states furiously work to complete their vote tabulations.

An already close race appeared to narrow even further, with more votes being counted in four key states that The Associated Press, which NPR relies on for calls, has yet to announce: Georgia, Nevada, North Carolina and Pennsylvania. The AP has also yet to call Alaska.

After calls by the AP in the key states of Arizona, Michigan and Wisconsin, Biden holds an Electoral College advantage of 264 votes to Trump's 214. That leaves both candidates with viable paths to victory.

Here's what remains undecided.

Georgia

Georgia is one of two Sun Belt states on which Democrats pinned high hopes of flipping. After Trump surged to an early lead, Biden has cut into that significantly. With 99% of the expected vote in, the president was clinging to a narrow lead of fewer than 10,000 votes out of nearly 5 million cast at 4:58 p.m. ET, according to AP data.

As of Thursday afternoon, there were roughly 50,000 votes left to be tallied, mainly from the cities of Atlanta and Savannah, The Atlanta Journal-Constitution reports. If Georgia, with its 16 electoral votes, flips to Biden, it will be the first time a Democratic presidential candidate has won the state since 1992.

Nevada

Nevada and its six electoral votes has been trending for the Democrats in recent elections, as the Latino population has increasingly become an important voting bloc in the state. The AP indicates that with 76% of votes tallied as of Thursday afternoon, Biden has increased his lead to about 11,000 votes, up from less than 8,000 earlier in the day.

Election officials in Clark County, which includes the Democratic stronghold of Las Vegas, said at a news conference Thursday that they expect to have the bulk of their outstanding ballots tabulated by this weekend.

North Carolina

North Carolina, another Sun Belt state that Democrats were hoping to turn blue, surged early for Trump. With 94% of the expected vote tallied, according to the AP, Trump maintains an advantage of more than 76,000 votes as of 2:02 p.m. ET Thursday.

The North Carolina State Board of Elections said on Wednesday morning that there were more than 116,000 outstanding absentee ballots. In September, the agency announced that county officials can accept mail-in ballots through Nov. 12 as long as they were postmarked by Election Day. The state carries 15 electoral votes.

Pennsylvania

With 20 electoral votes at stake, the Keystone State is the biggest state still up for grabs. While Pennsylvania has nearly 90% of its vote tallied, there were still roughly 340,000 mail ballots still to be counted as of Thursday afternoon, according state election officials.

Throughout the day Thursday, Trump has seen a steady decline in the slim lead he had in the state. Shortly before 5 p.m. ET Thursday, his advantage was a little more than 90,000 votes — down from what was an early lead of around 700,000 votes. That suggests mail-in voters are heavily going toward Biden. Unlike other states, Pennsylvania was not able to begin processing mail-in ballots until Election Day, and it can continue counting ballots received by Nov. 6 if they were postmarked by Nov. 3.

Alaska

There is less suspense in Alaska, a state President Trump is widely expected to win. With 50% of the vote in, the AP has Trump up by around 54,000 votes. More than 190,000 votes have already been counted, but as Alaska Public Media reported Wednesday, election officials had more than 100,000 ballots still to count. The state has three electoral votes.

Jess Eng (Twitter: @jessicaeng17) is an intern with NPR's News Apps team.

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Correction

A graphic previously included with this story showing estimates for the number of votes remaining to be counted in Georgia, Pennsylvania, Nevada and North Carolina has been removed due to discrepancies in estimates of the states' expected vote totals and figures being reported by the states.