In Econ 101, when you study supply an demand, you also study elasticity and inelasticity. In certain situations demand may rise in the form of higher wages but the supply is inelastic so it doesn't grow.
The labor supply has a degree of inelasticity because it takes 20 years to produce a new worker.
And sometimes supply may increase not within the market, but outside the market. We might be able to get that chicken cheaper by importing it from Mexico or China. Or, I don't want to pay that price for chicken so I substitute tuna. Or, the chicken processor facing tight labor supplies will respond by not trying to produce more product(birds) but by producing more valued added product such as a cooked bird so he can make more money per bird.
Looking at the CIA factbook stats we have a birth rate 13.42 per 1000 and an immigration rate of 2.45 per 1000 and when you subtract out the death rate we end up with a population growth rate of 0.77% per year. But each year the median age of the workforce increases
I worked post Katrina Const. the employment office was the Home Depot. prob 40 to 50 always there. All Mexicans.
Or two weeks without a welfare check.