The 2020 Census Project is a pooled fund for left-of-center donors and foundations interested in shaping the 2020 Census to favor traditionally Democratic-leaning constituencies, particularly in cities. The project is fiscally sponsored by the left-of-center New Venture Fund, a 501(c)(3) funding and fiscal sponsorship managed by the for-profit consulting firm Arabella Advisors in Washington, DC. 
Unlike many other Arabella projects, the 2020 Census does not have its own website but has received substantial funding from multiple major left-of-center funders.
Activities and the 2020 Census
The 2020 Census Project is closely related to a donors affinity group, the Democracy Funders Collaborative, which was instrumental in creating the group. The collaborative is composed of many many left-of-center foundations and donors, including the Annie E. Casey Foundation, Ford Foundation, Carnegie Corporation of New York, JPB Foundation, Open Society Foundations, Kresge Foundation, the Rockefeller Brothers Fund, W. K. Kellogg Foundation, Bauman Foundation, Joyce Foundation, Heising-Simons, Unbound Philanthropy, Wallace A. Coulter Foundation, James Irvine Foundation, California Endowment, and the Hewlett Foundation.
For more information, see Democracy Funders Collaborative | 2020 Census Project
The 2020 Census Project is a fiscally sponsored project of the New Venture Fund, a Washington, DC-based 501(c)(3) nonprofit. As such it does not file Form 990 reports with the IRS and all grants to it are paid to the New Venture Fund.