Census self-response data is used to monitor the progress and accuracy of a community's population count. When households complete the census independently, it yields higher-quality data and significantly reduces administrative costs by minimizing the need for door-to-door follow-ups. By analyzing these response rates in real time, government officials and local organizations can identify underrepresented neighborhoods and strategically deploy resources, such as language assistance or outreach campaigns. Ultimately, achieving a high self-response rate is essential for ensuring that a community receives its equitable share of federal funding for infrastructure, healthcare, and education, while also securing accurate political representation.

In 2020, 69.3% of the county's households self-responded to the 2020 Census, up 1.4 percentage points from 2010. This was higher than both state and national rates (64.2% and 67%, respectively). Among comparison counties, Westchester County had the lowest rate behind Nassau County (74.9%), Putnam County (71.9%) and Rockland County (71.1%).

Within Westchester County, self-response rates ranged from lows of 57.4% in Port Chester and 58% in Mount Vernon to highs of 82.6% in Pelham Manor and 84.1% in Scarsdale. Most municipalities saw increases in self-response rates from 2010 to 2020.

The self-response rate reflects the households that responded online using the internet survey site, by providing information to a phone interviewer through Census Questionnaire Assistance, or by completing and returning a paper questionnaire. The self-response rate is the number of unduplicated responses received by any self-response mode divided by the number of housing units, including deleted and vacant units.