Lancashire won their first title in 77 years after a dramatic final session, while Yorkshire and Hampshire were relegated from Division One.
Lancashire finished as champions with 246 points after 10 wins, two draws and four defeats after a thrilling run resulting in an eight-wicket victory against Somerset at Taunton.
Somerset posted 386 in their first innings thanks to James Hildreth's 186 and 68 from Jos Buttler. Gary Keedy took 4-57 for the away side.
Contributions all down the order allowed Lancashire to reply with 480. Stephen Moore hit 68, Karl Brown 60, Steven Croft 54 and Paul Horton 50. Murali Kartik picked up 5-137.
Somerset slipped to 130-7 and the title looked to be in Lancashire's hands but, Peter Trego (120) and Murali Kartik (65 not out) dragged the home side to 310.
An injured Glen Chapple took 3-53 and Simon Kerrigan 3-109 with Gary Keedy running out Gemaal Hussain for the final wicket for his first direct hit run out in his career.
Lancashire needed 211 for victory and reached their target from 29.1 overs with 29 balls to spare to win by eight wickets. Stephen Moore smashed 71 from 55 balls and Paul Horton 55 from 49 balls.
Somerset finish fourth on 189 points with six wins, three draws and seven defeats.
Warwickshire had to be content with second place on 235 points after they failed to bowl out Hampshire on the final day of their match at the Rose Bowl.
Warwickshire posted 493 in their first innings with Shivnarine Chanderpaul making 171 and Varun Chopra 109. Dimitri Mascarenhas took 3-52 and Chris Wood 3-87.
Liam Dawson carried his bat for his 152, not out, but could not prevent Hampshire from failing to avoid the follow on target as they were bowled out for 324. Chris Metters took 3-71 and Chris Wright 3-77.
Following on, Michael Carberry (111) and Neil McKenzie (115 not out) ensured Hampshire were 327-7 before the match ended as a draw. Metters took 5-115 but it was in vain as Warwickshire finished runners-up.
Warwickshire won nine, drew three and lost four of their games this season.
Hampshire are relegated after finishing bottom on 127 points with three wins, seven draws and six defeats.
Durham finish third on 232 points with eight wins, four draws and four defeats after a 151-run victory against Worcestershire at Chester-le-Street.
Durham posted 264 first time around as Will Smith made 66. As soon as the third Durham wicket fell, Worcestershire picked up the bonus point they needed to relegate Yorkshire. Alan Richardson took 3-46 and Kemar Roach 3-57.
Worcestershire collapsed from 255-3 to 288 despite Vikram Solanki's 124 and James Cameron's 74. Callum Thorp picked up 4-52, Paul Collingwood 2-31 and Graham Onions 2-50.
The home side made 388 in their second inning with Mark Stoneman hitting 75 and Dale Benkenstein 63. Gareth Andrew claimed 4-72 and Richardson 3-43.
Chasing 365, but knowing they were safe in Division One, Worcestershire fell away to 213 to lose by 151 runs. Scott Borthwick took 3-25 and Ian Blackwell 3-67 to secure Durham's victory.
Worcestershire finished seventh on 142 points and avoided relegation despite losing 11 of their 16 games.
Sussex finish fifth on 182 points after an innings and five-run victory against 2010 champions Nottinghamshire at Trent Bridge.
Sussex piled on 488 in their first innings, with Murray Goodwin smashing 170 and Matt Machan 71. Andre Adams returned 5-110 and Charlie Shreck 3-92.
Nottinghamshire slipped from 206-2 to 311 all out as Karl Turner made 64, Chris Read 55 and Darren Bravo 53. Monty Panesar claimed 3-60 and Naved Arif 3-86.
Following on, Nottinghamshire were bundled out for just 172, as Naved Arif took 4-41 to give Sussex an innings and five-run victory.
Nottinghamshire finish sixth on 173 points with five wins, five draws and six defeats.
Yorkshire have been relegated in eighth place with 138 points. They won three, drew seven and lost six of their four-day games.
Next season sees Middlesex and Surrey join County Championship Division One in place of relegated Yorkshire and Hampshire.
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