If you pick "All Americans" that statistic is probably close since 1/2 of the Americans are too young for a BA/BS

. I think if you look at the age group here you will find that far more then that have a college degree, especially considering the number of baby boomers in the country right now and the older end of that generation did not go to college at the rate the say 60 and under crowd did/does.
I know in our county, 60% of adults over 24 have a college degree according to the county website.
The US Census website says that the breakdown of age groups /bachelor's degrees earned looked like this in 2008:
US population 18-24 years of age: 9%
US population 25 - 34 years of age: 29.2%
US population 35 - 44 years of age: 30.4%
US population 45 - 64 years of age: 28.8%
US population 65+: 19.4%
Website address:
http://factfinder.census.gov/servle...501&-ds_name=ACS_2008_3YR_G00_&-redoLog=false
The 18-24 year old figure was lower than I would've expected.
I looked at a couple other sites, and I could find no site that didn't specify adults only. So they're not including the kids. That would certainly be poor -- even deceptive -- methodology.
I do think you have a point when you say that the older population had less opportunity to earn a college degree -- and that shows in these stats. I'm sure that if you could see the 65+ group broken down into smaller categories, you'd find fewer degreed individuals among the 80-year olds and more among the 60-year olds. Remember, though, that college became an affordable goal for middle class individuals with the GI bill -- and the 60-somethings were among the first to take advantage of that benefit.
You also have a point when you specify your specific county. If you were to come to my area, you'd find a higher percentage of degreed individuals right here in my immediate area. Why? Because we're a suburb of a big city that employs many people in banking and because we have a regional hospital just a few miles down the road, which employs many highly-trained medical professionals. However, if you move north one county you'll find factory workers, if you move south one county you'll find small family farms, and if you move east one county you'll find inner city ghettos -- none of those areas have large numbers of degreed individuals. If you travel a few hours east, you'll reach the Triad area, which houses many research firms and several major universities -- I'm certain you'd find more PhDs in a 25-mile radius than in the whole state put together. Pinpointing an area will absolutely change the results.
I don't doubt that your specific area can boast that 60% of its population is degreed, but it's not true of the country as a whole.