Finding 6 — State policy as the lever

Policy score × youth turnout (2020 + 2022 + 2024 pooled)

The policy score sums six policies, sourced from the National Conference of State Legislatures (NCSL):^[6]

• Automatic Voter Registration (AVR) — registers eligible citizens at the DMV unless they opt out
• Same-Day Registration (SDR) — register and vote on the same day at the polls
• Online Voter Registration (OVR) — register via a state web portal
• Pre-registration at 16 or 17 — 16- and 17-year-olds can register before they turn 18
• No-excuse absentee voting — request a mail ballot without needing a specific reason
• Universal Vote-by-Mail (VBM) — every eligible voter is mailed a ballot automatically

Values range from 0 (none of the six in effect) to 6 (all six in effect).

Policy score × youth-senior gap

The same relationship viewed through the gap lens: states with higher policy scores tend to show smaller senior-youth gaps. This is the turnout finding above seen from the gap angle — the same state-years, so it restates rather than adds. The points are available below for readers who want them.

Literature-supported causal effects

For two policies the peer-reviewed literature supports direct causal attribution for youth turnout effects, beyond the correlational view above:

• Same-day registration. Peer-reviewed estimates put the youth-specific effect in the range of +3 to +5 percentage points (Gerber & Green 2019, synthesizing multiple studies).^[13] This is one of the largest single-policy effects documented for the 18-29 cohort.
• Mail-ballot expansion / universal VBM. Peer-reviewed estimates place the turnout effect in the range of +2 to +5 percentage points, with stronger effects for low-propensity voters (Gerber & Green 2019; Gronke et al. at Reed EVIC).^[13][14] Youth effects are at the upper end of this range.

For the remaining four policies (AVR, OVR, pre-registration, no-excuse absentee), the causal literature is moderate-to-strong in support of an effect but less precisely estimated for the youth sub-cohort specifically. The correlational finding above is consistent with the literature but should not be read as establishing causation state-by-state.

What this page establishes

1. Higher state policy scores correlate with higher youth turnout in the 2020-2024 state-year panel.
2. The policy effect is youth-asymmetric. State policy variation explains more variance in youth turnout than in overall turnout.
3. Causal evidence concentrates on two levers — same-day registration and mail-ballot expansion — where the peer-reviewed youth effect range is +2 to +5 pp per policy.
4. Correlation is not uniform across groups. States where the policy-score lift is largest are those with the highest access-barrier responses among non-registrants (see Finding 3 cross-cut).

Cross-references

• Finding 3 — Who didn't register, and why — the access-barrier diagnostic these policies address
• Finding 5 — Method preference — revealed method use by state regime
• Recommendations — cost-per-marginal-voter ranges for each policy

So what

For Secretaries of State. Your state's current policy score places it in one of the access groups above (and on the full scatter, if you expand it). A one-unit move up the policy score is associated with an average youth-turnout change consistent with the literature ranges. State-Gap Explorer and Finding 3 let you identify which specific barrier is most cited by your state's non-registrants, directing attention to the policy that addresses that barrier.

For foundation officers. Policy-reform grantmaking sits at the $0-$5 per-marginal-voter end of the ROI catalog — dramatically lower than programmatic get-out-the-vote (GOTV) — because the per-cycle cost amortizes once the policy is in force.^[13][14][15] The evidence strongest for same-day registration and mail-ballot expansion.

For the public. Where you live meaningfully shapes how much time, paperwork, and pre-planning it takes to register and vote. State policy variation is not about candidate preference; it is about the operational cost of participation.