(NewsNation) — Several states across the United States allow their constituents to vote by mail, which can make the voting process far more streamlined for individuals.

However, there have been concerns that mail-in, or absentee, ballots are inefficient or may be unable to be counted.

Voters can request their ballots via USA.gov and Vote.org. They can also track their ballot status here.

With Election Day closing in, NewsNation has all you need to know about mail-in voting.

What to know about mail-in ballots

Dating back to the Civil War, mail-in voting has been an institution of U.S. elections. The frequency of mail-in voting increased during the COVID-19 pandemic.

There are varying ways in which someone can qualify for mail voting; absentee voting (excuse or no-excuse) and standardized mail voting.

Which states allow mail-in voting?

Every state allows mail-in voting, but the degree to which varies.

All-mail elections occur predominantly on the West Coast. This means constituents will receive a ballot at their residence and can mail in their ballots, or vote in person.

California, Colorado, Hawaii, Nevada, Oregon, Utah and Washington all allow mail voting under all circumstances. The only other state in the nation to have such practices is Vermont. Washington D.C. also allows all-mail voting.

Twenty-eight states have a no-excuse absentee policy, meaning voters don’t need to explain themselves to receive a mail-in ballot.

These include Alaska, Arizona, Florida, Georgia, Idaho, Illinois, Iowa, Kansas, Maine, Maryland, Massachusetts, Michigan, Minnesota, Montana, Nebraska, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Dakota, Virginia, Wisconsin and Wyoming.

Which states don’t allow mail-in ballots?

All states allow absentee voting, but a worthy excuse must be provided in the following states:

Alabama: Out of county, illness/disability, caregiver, working during voting hours, student living outside of the county, election worker, incarcerated (not convicted of “moral turpitude”), aged 65+, caregiver, military service, religious beliefs/practice.

Arkansas: Out of county, illness/disability, caregiver, uniformed services member.

Connecticut: Out of county, illness/disability, caregiver, election worker, armed forces member, religious beliefs/practice.

Delaware: Out of county, illness/disability, caregiver, working during voting hours, religious beliefs/practice, armed forces member.

Indiana: Illness/disability, caregiver, out of the county, work, religious reasons, aged 65+, election worker, armed forces or public safety officer, “serious sex offender”, state address confidentiality program.

Kentucky: Out of county, illness/disability, caregiver, state address confidentiality program, elderly age.

Louisiana: Out of county, illness/disability, caregiver, state address confidentiality program, elderly age, military forces, aged 65+, involuntary confinement, incarceration, jury duty, religious practices.

Mississippi: Out of county, illness/disability, aged 65+, work, caregivers, incarceration for a non-disenfranchising crime.

Missouri: Out of county, illness/disability, religious beliefs/practices, election worker, essential worker, incarceration, state address confidentiality program.

New Hampshire: Out of county, illness/disability, caregiving, work, religious beliefs/practices, incarceration, state address confidentiality program, protected by domestic violence protective order.

South Carolina: Out of county, illness/disability, caregiving, work, aged 65+, incarceration, armed forces.

Tennessee: Out of county, illness/disability, caregiving, work, aged 60+, reside in a nursing home, religious beliefs/practices, election worker, jury duty, military member.

Texas: Out of county, illness/disability, work, expectant within three weeks before or after Election Day, incarceration.

West Virginia: Out of county, illness/disability, work, state address confidentiality program, incarceration, first responder.

How are mail-in votes counted?

According to the National Conference of State Legislatures, in 31 states voters must sign an affidavit on their ballot envelope which helps ballot workers verify their signature against their voter registration record.

Ten states require a copy of personal identification or the ballot to be notarized or have a witness signature — Alabama, Alaska, Louisiana, Minnesota, Mississippi, Missouri, North Carolina, Oklahoma, South Carolina, and Wisconsin.

Ten other states — Connecticut, Delaware, District of Columbia, Georgia, Maryland, Nebraska, New Mexico, Pennsylvania, Vermont, Virginia, and Wyoming — plus Washington D.C., verify that a signature is on an absentee, but do not verify the signature itself.

What are the pros and cons of mail-in voting?

Proponents of absentee voting suggest it is a more cost-effective measure than in-person voting. It also allows for greater convenience and increased participation, particularly for those who would not be able to vote due to work or geographical constraints, among others.

The primary concern of mail-in and absentee voting is the integrity of elections and the threat of voter fraud.

There are several concerns about the numerous ways mail-in ballots can be tampered with; whether it be undue influence over the individual’s ballot when it is cast, unfilled ballots being collected and voters making their selection before all information from the respective campaigns has been revealed.

However that notion can be countered by earlier voters tending to be more partisan compared to undecided voters.