ABA Transit Numbers were developed by the American Bankers Association in 1910 to indicate check processing endpoints. Since then, the numbers' use has expanded to include participants in check clearing between banking institutions, automated clearing houses and online banking activities. The numbers are also used in Fedwire transfers. The ABA routing number appears in two forms on most checks: as a machine-readable nine-digit number on the bottom left (followed by the checking account number), and as a fraction at the top. The first form, known as the magnetic ink character recognition (MICR) form, is the one used to actually process checks.