Minimum Wage Rate was Higher in Real Terms in 1968

The minimum wage rate, in real terms, was higher in 1968 than it is today: $10.59/hour. So why is the President proposing $9/hour? And why did it take him 4 years to come out for an increase? The White House is claiming that raising the rate would benefit the economy. So wouldn't it have made sense to see to raise it in 2009?