What is The Purpose of Address Line 2?

If you've ever mailed a letter or package, you'll know that there are specific addressing guidelines that must be followed in order for your mail to arrive at the right place. These guidelines help ensure that your mail can be delivered on time, and that it is correctly sorted when it arrives. 

For example, the United States Postal Service requires that each address be written in a manner that clearly identifies which part of the delivery address is for residential use, and which is for business use. When delivering to business addresses, the first line of the delivery address must include the recipient's name, while the second line of the address should be reserved for secondary address designators such as suite, apartment, office, floor, or room number.

Many online forms include an "Address Line 2" field to allow users to enter these additional address designators. Often, this information is then used in address verification processes to confirm that the address submitted actually matches the intended destination of a shipment.

While this is an important feature to have, we've found that it can be confusing for some end users. In fact, our eye-tracking testing has shown that hiding this field behind a link can alleviate this issue by showing users one less form field by default, and making it feel less intimidating. In addition, it can be an effective solution for sites that need to meet USPS addressing requirements but do not want to force all users to add this extra address line.