Beginning in 2013, the American Community Survey (ACS) added a new way for people to respond to the survey, by using the Internet. With the addition of this new data collection mode, respondents could now complete the survey in five different ways: Internet, mail, telephone questionnaire assistance (TQA), computer-assisted telephone interview (CATI), or computer-assisted personal interview (CAPI). Because of the availability of five response modes, the ACS must allow for the possibility of receiving multiple surveys from the same address: for example, an internet survey AND a mail survey, a telephone interview AND an internet survey, etc. In fact, the ACS has found that about 1.45 percent of sample housing units return more than one survey. To handle these cases of multiple returns for a single housing unit, the ACS developed an algorithm, called the Primary Selection Algorithm, to select just one survey from among the ones submitted. The purpose of this research project is to explore how the addition of the internet as an additional response mode impacts the survey chosen by the Primary Selection Algorithm.