If you live in the USA, by choosing to purchase clothing that is Made in the USA, you're keeping your carbon footprint lower, helping to reduce pollution, and helping to build a stronger economy.
Products that are made overseas have a higher carbon footprint then a garment that is Made in America. As any goods made in across the world or in another country have to be shipped, which burns fossil fuels and spews greenhouse gases for each mile they must travel.
Many developing countries that are common for garment production, have few or sometimes zero regulations on to protect the air or water.
By voting with your dollar and purchasing your clothing (or anything else) from a company that produces its products in the USA, you are helping to create more jobs. Think of the ripple effect, as an American company grows, they will hire other American companies to help with everything from construction to accounting.