That is an increase of 1.8 million voters just since the last presidential election in 2016 — a 12-percent increase in voters.

Nowhere have the gains been greater than along Interstate 35 — a region that has become a blue spine in the heart of an otherwise red state. Of the 1.8 million voters added since 2016, half have come from the 21 counties that stretch from Laredo north into San Antonio, Austin, Waco and the Dallas-Fort Worth region.

The biggest percentage increase has been in Central Texas where Hays, Williamson and Comal counties have all seen their voter registration rolls grow by 24 percent or more. Further north, outside of Dallas, suburban Collin and Denton counties have seen voter rolls grow 19 percent and 21 percent respectively.