Disclaimer: General educational research only — not legal, medical, tax or financial advice. Rules differ by state and by family. Talk to an estate planning attorney in your state before you act.
On July 1, 2025, 4,499,944 Americans were 17 years old, according to the Census Bureau’s Vintage 2025 population estimates. Almost all of them turn 18 within a year. That’s about 12,329 new adults a day.
The birthday changes more than most families expect. In most states, the day a child turns 18, parents stop being their legal decision-makers. If that young adult is badly hurt at college, the hospital decides how much to share with Mom or Dad, and whether they can make medical decisions depends on state default rules that may not fit the situation. A few short documents remove the guesswork.
Parents of teens: the plan you signed when your kids were small may hand everything to them outright at 18. See whether a trust or a will fits your family now.
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Key findings
- 4,499,944 people were 17 in mid-2025, and 4,515,570 were 18 (Census Vintage 2025). About 12,329 turn 18 every day.
- 31,936,859 Americans are 18 to 24, 9.3% of the population.
- Most 17-year-olds: California (526,308), Texas (460,475), Florida (277,994), New York (240,324) and Illinois (167,823).
- Highest per 1,000 residents: Utah (16.8), Idaho (14.9), Mississippi (14.6), Texas (14.5) and Oklahoma (14.5). These states have the largest share of families about to cross this line.
- Lowest per 1,000 residents: District of Columbia (8.2), Maine (11.2), New Hampshire (11.3), Hawaii (11.4) and Vermont (11.5).
- Three states set adulthood later for many purposes: Alabama and Nebraska at 19, and Mississippi at 21. Federal school-record rights still move to the student at 18 or on starting college.
Turning 18 by state
| State | Age 17 (turning 18 within a year) | Age 18 | Ages 18 to 24 | 17-year-olds per 1,000 residents |
|---|---|---|---|---|
| California | 526,308 | 526,579 | 3,684,287 | 13.4 |
| Texas | 460,475 | 448,620 | 3,151,665 | 14.5 |
| Florida | 277,994 | 277,582 | 1,948,980 | 11.8 |
| New York | 240,324 | 262,105 | 1,838,192 | 12.0 |
| Illinois | 167,823 | 167,768 | 1,187,061 | 13.2 |
| Pennsylvania | 159,660 | 168,197 | 1,186,683 | 12.2 |
| Georgia | 158,959 | 150,636 | 1,086,284 | 14.1 |
| Ohio | 155,427 | 151,071 | 1,073,107 | 13.1 |
| North Carolina | 144,673 | 149,633 | 1,071,492 | 12.9 |
| Michigan | 129,996 | 126,517 | 941,157 | 12.8 |
| New Jersey | 123,073 | 123,325 | 826,338 | 12.9 |
| Virginia | 116,169 | 121,552 | 837,072 | 13.1 |
| Arizona | 102,047 | 102,753 | 742,283 | 13.4 |
| Washington | 99,095 | 95,907 | 688,448 | 12.4 |
| Indiana | 96,812 | 97,471 | 686,246 | 13.9 |
| Tennessee | 96,347 | 92,439 | 668,056 | 13.2 |
| Massachusetts | 84,736 | 93,996 | 706,187 | 11.8 |
| Maryland | 83,897 | 80,816 | 549,048 | 13.4 |
| Missouri | 83,812 | 80,989 | 586,821 | 13.4 |
| Minnesota | 79,302 | 75,942 | 531,486 | 13.6 |
| Wisconsin | 77,566 | 79,170 | 567,363 | 13.0 |
| Colorado | 76,707 | 77,399 | 561,081 | 12.8 |
| South Carolina | 72,562 | 77,136 | 510,476 | 13.0 |
| Alabama | 68,718 | 71,670 | 500,763 | 13.2 |
| Louisiana | 64,642 | 63,533 | 436,996 | 14.0 |
| Kentucky | 62,469 | 60,777 | 426,651 | 13.6 |
| Oklahoma | 59,626 | 57,610 | 415,434 | 14.5 |
| Utah | 59,496 | 57,232 | 428,633 | 16.8 |
| Oregon | 52,627 | 50,368 | 372,167 | 12.3 |
| Connecticut | 46,716 | 51,081 | 348,096 | 12.7 |
| Iowa | 45,040 | 45,475 | 328,514 | 13.9 |
| Arkansas | 43,340 | 43,123 | 296,779 | 13.9 |
| Mississippi | 43,043 | 45,055 | 293,811 | 14.6 |
| Kansas | 42,595 | 43,023 | 310,361 | 14.3 |
| Nevada | 42,516 | 39,390 | 270,053 | 13.0 |
| Idaho | 30,299 | 29,883 | 203,927 | 14.9 |
| New Mexico | 29,706 | 28,970 | 209,298 | 14.0 |
| Nebraska | 29,184 | 28,690 | 204,750 | 14.5 |
| West Virginia | 22,240 | 22,359 | 159,081 | 12.6 |
| Hawaii | 16,275 | 14,629 | 118,345 | 11.4 |
| New Hampshire | 15,946 | 16,081 | 120,042 | 11.3 |
| Maine | 15,814 | 17,872 | 115,472 | 11.2 |
| Montana | 14,642 | 14,172 | 105,331 | 12.8 |
| Rhode Island | 13,284 | 15,802 | 112,237 | 11.9 |
| South Dakota | 13,159 | 12,884 | 90,160 | 14.1 |
| Delaware | 13,020 | 12,752 | 92,683 | 12.3 |
| North Dakota | 10,279 | 11,592 | 91,525 | 12.9 |
| Alaska | 10,014 | 9,120 | 68,091 | 13.6 |
| Wyoming | 8,337 | 8,274 | 56,173 | 14.2 |
| Vermont | 7,445 | 8,975 | 62,947 | 11.5 |
| District of Columbia | 5,708 | 7,575 | 68,726 | 8.2 |
| United States | 4,499,944 | 4,515,570 | 31,936,859 | 13.2 |
Source: U.S. Census Bureau, Vintage 2025 Population Estimates, state resident population by single year of age, July 1, 2025. Sorted by number of 17-year-olds.
What changes at 18
- Medical decisions and records. Under federal HIPAA rules, a parent is usually the “personal representative” of a minor child. For an adult, the personal representative is someone with legal authority to make health care decisions, such as an agent under a health care power of attorney or a court-appointed guardian. A parent who isn’t named in a document doesn’t automatically qualify. Doctors may still share some information with family who are involved in care, but that is up to the provider.
- School records. Under the federal FERPA law, rights to education records move from parents to the student at 18, or when the student enrolls in college at any age.
- Money and accounts. A parent can’t sign for an adult child’s bank account, lease, tax notice or student loan without a power of attorney.
- If something serious happens. Without documents, a family may need to ask a court to appoint a guardian before they can make decisions. That takes time and money, often when there is least of both.
The three documents every new adult should sign
- Health care power of attorney (or health care proxy). Names who makes medical decisions if the young adult can’t. Many states publish a standard form.
- HIPAA authorization. Lets doctors and hospitals share health information with the people named. It’s often included in the health care form, but a separate one is easy to add.
- Durable financial power of attorney. Lets a trusted person handle accounts, bills and paperwork. College students studying abroad or far from home find this especially useful.
Two more steps help: name beneficiaries on any new job’s retirement plan or life insurance, and think about a simple will once the young adult owns a car, has savings or has children of their own. Without a will, an adult child’s property usually passes to their parents or siblings under state law, through probate.
What parents should update
- Check what your will leaves to your kids, and when. Many parents’ wills name a guardian and leave everything to the children equally. Once a child is 18, a guardian no longer applies, and a gift left outright goes straight to them.
- Know when custodial accounts end. Money in a UGMA or UTMA custodial account belongs to the child, and the custodian must turn it over at an age set by state law, usually 18 or 21. A trust lets you choose later ages or hand money out in stages.
- Review beneficiary forms. Life insurance and retirement accounts that name a minor child may need a court-appointed guardian or conservator to manage the money. Naming a trust can avoid that for younger siblings.
- If your child has a disability, turning 18 is the point to consider supported decision-making, a power of attorney or, when needed, guardianship. A special needs trust can protect eligibility for SSI and Medicaid. See children with disabilities by state and the SSI asset limit and special needs trusts.
An example
A 19-year-old college sophomore is hurt in a bike accident two states from home. She is unconscious. Her parents fly in, but the hospital treats her as an adult, and they have no document naming them. If she had signed a health care power of attorney and HIPAA authorization before leaving for school, they could talk with her doctors and make decisions right away. Without them, the hospital follows state default rules, which in many states let close family make decisions but can lead to delays or a guardianship case if relatives disagree.
Related: new parents by state · who would raise the kids? · turning 65 by state · estate planning for new parents
Related research: student loans after death by state covers what happens to Parent PLUS and cosigned private loans if a parent or student dies.
Methodology
We used the Census Bureau’s Vintage 2025 state population estimates by single year of age (file sc-est2025-alldata6), downloaded Oct. 20, 2026. We summed all race and Hispanic-origin groups for both sexes to get each state’s July 1, 2025 resident population at ages 17, 18 and 18 to 24. The U.S. figure is the sum of the 50 states and D.C. We cross-checked the 17-year-old counts against the Census civilian population file; they match within 0.1% nationally (the gap is mainly 17-year-olds on active military duty).
The number of 17-year-olds is a stand-in for people turning 18 in the following year. It doesn’t adjust for deaths or for moves between states, so it’s an approximation. The daily figure divides by 365.
What this doesn’t measure. These are modeled estimates built from the 2020 Census plus births, deaths and migration, not a survey, so Census doesn’t publish margins of error for them. The data can’t tell us how many young adults have signed a health care proxy or power of attorney. Age-of-majority rules come from state law: Alabama Code 26-1-1 (19), Nebraska Revised Statute 43-2101 (19, with some rights at 18) and Mississippi Code 1-3-27 (21 for many purposes, 18 for property contracts).
Frequently asked questions
Do parents need a power of attorney for an 18-year-old?
In most states, yes, if they want legal authority to make medical or financial decisions or see records. Once a child is an adult, parents don’t have that authority automatically.
What is a HIPAA authorization?
A signed form that lets health care providers share your health information with the people you name. It doesn’t give anyone decision-making power. A health care power of attorney does that.
How many people turn 18 each year?
About 4.5 million. Census counted 4,499,944 17-year-olds on July 1, 2025.
Does an 18-year-old need a will?
Not always. It becomes more important once they have a car, savings, a retirement account or children. Without a will, state law decides who inherits.
Is this legal advice?
No. Talk to an estate planning attorney in your state.
Sources
Public-domain government sources only. Fetched 2026-10-20.
Data
- U.S. Census Bureau, State Population by Characteristics: 2020-2025, single year of age (sc-est2025-alldata6): https://www2.census.gov/programs-surveys/popest/datasets/2020-2025/state/asrh/
- U.S. Census Bureau, Population Estimates Program: https://www.census.gov/programs-surveys/popest.html
Rules and definitions
- U.S. Department of Health and Human Services, HIPAA Personal Representatives guidance (45 CFR 164.502(g)): https://www.hhs.gov/hipaa/for-professionals/privacy/guidance/personal-representatives/index.html
- U.S. Department of Education, Student Privacy Policy Office, What is FERPA?: https://studentprivacy.ed.gov/faq/what-ferpa
- Office of the Comptroller of the Currency, HelpWithMyBank.gov, What is a UGMA or UTMA account?: https://www.helpwithmybank.gov/help-topics/investments-trusts/uniform-gifts-to-minors-account/ugma.html
- Code of Alabama, Section 26-1-1: https://alison.legislature.state.al.us/code-of-alabama?section=26-1-1
- Nebraska Revised Statute 43-2101: https://nebraskalegislature.gov/laws/statutes.php?statute=43-2101
- Mississippi Code Section 1-3-27 (Mississippi Legislature)
Related data
More in Income, benefits, disability and life stages.
Cite this data
Family Estate Guide, “Turning 18 by State,” October 2026. https://familyestateguide.com/estate-planning-data/turning-18-by-state/
You’re welcome to reuse the table with a link back to this page. The underlying government data is public.
Published October 20, 2026 by Family Estate Guide. Data vintage: Census Vintage 2025 population estimates (July 1, 2025). Editorial standards.