Voters are voting!

All eyes in the political world are on South Carolina where the state that has picked the eventual Republican presidential nominee in every election since 1980 will make its choice today.

The shadow of Republican presidential candidate Rep. Ron Paul, R-Texas, is cast against the South Carolina state flag as he waits to be introduced at a campaign rally in an airplane hanger Friday, Jan. 20, 2012, in North Charleston, S.C. (AP Photo/David Goldman)

But, we also thought it made sense to provide a cheat sheet for Fixistas as they watch the returns flow in. (Here’s a good place to monitor South Carolina returns.)

Below are five counties to keep an eye on tonight. They’ll be leading indicators of where the primary is headed.

(And, as a special bonus, at the end of this post is a detailed county-by-county look at the 2008 South Carolina presidential primary, complete with projections of how Mitt Romney needs to perform relative to Newt Gingrich — and vice versa — to win the state today.)

1. Beaufort County

This was Romney’s best county – by far – in 2008, when he took 26 percent of the vote in this southeastern coastal area. It’s also the most moderate-friendly county, having given nearly three-quarters of the vote to the trio of Romney, John McCain and former New York mayor Rudy Giuliani.

The ninth-biggest county in the 2008 results, it has grown even more since then as northern retirees continue to move south. Romney should do very well here, and if he doesn’t, that’s a bad sign.

One caveat, though, is that Rick Santorum’s brother is from here, and Romney hasn’t visited much (see our visit tracker here), so the former Pennsylvania senator could steal votes and play spoiler.

2008 results: McCain 42, Romney 26, Mike Huckabee 16, Fred Thompson 8, Giuliani 6, Ron Paul 2

2.Greenville County

By far the state’s biggest county, it accounts for more than one in eight primary voters, so of course it’s important. But it’s also noteworthy because it was so close in 2008 – the closest among the state’s 10 most populous counties, with Huckabee beating McCain by three points.

If Romney can somehow win here, that would be a very good sign and a big help in the raw vote count as well. Gingrich robably needs a win here.

2008 results: Huckabee 29, McCain 26, Thompson 21, Romney 17, Paul 5, Giuliani 2

3. Horry County

Located in the far eastern reaches of the Palmetto State, Horry County is the home of beach-loving transplants from the Northeast and Midwest. As such, it is just as fiscally conservative but far less socially conservative than areas in the Upstate area — Greenville/Spartanburg, etc.

This has to be Romney territory — and strongly so — if he wants to win.

2008 results: McCain 33, Huckabee 28, Romney 19, Thompson 14, Giuliani 3, Paul 3

4. Lexington County

The second biggest county — by population — in the state also happens to be the best bellwether for statewide results.

In 2010, Gov. Nikki Haley, a native of this county, won it with 53 percent in a four-way Republican primary; she won the county by 11,000 votes, a major chunk of her 15,000-vote margin statewide.

The county is suburban — people who work in Columbia live here — and has seen tons of new residents move in over the past decade. Who wins it is a good indicator of who will win the state. The results here in 2008 track pretty closely to the statewide results.

2008 results: McCain 33, Huckabee 29, Romney 17, Thompson 16, Paul 3, Giuliani 2

5. York County

While Beaufort was the kindest to moderate candidates, York was most unkind. This suburban Charlotte county — the eighth-biggest in the 2008 primary — gave the trio of more moderate candidates just 37 percent of the vote and handed Huckabee a 12-point win. If Romney can be somewhat competitive here, he’s going to have a good night.

2008 Results: Huckabee 36, McCain 24, Thompson 23, Romney 11, Paul 4, Giuliani 2