It looks like you're new here. If you want to get involved, click one of these buttons!
Just to add to Michelli's answer,
The most recent Federal minimum wage increase was back in 2009, increasing to $7.25.
New Jersey's most recent change took place this year, on Jan 1st, and increased to $8.25.
These wages are calculated and reevaluated on a yearly basis based on what's known as the cost of living formula. While there is a federal standard for this formula, each state has its own version, which results in the vast variety of minimum wages that you see spread across each state.
Obviously, raising the minimum wage can have a massive impact on the state and/or country's economy, so it doesn't happen very frequently. That said, it's best to check the link Michelli provided every so often for changes to the minimum wage law or any other labor law.