1. Rubella
Rubella, otherwise known as German measles, causes only very mild symptoms in most people with healthy immune systems (largely a rash and swollen glands in the neck), but can be fatal or crippling to unborn children. If a woman contracts rubella while pregnant, there is, according to the Centers for Disease Control and Prevention (CDC), "an 80% chance that her baby will be born deaf or blind, with a damaged heart or small brain, or mentally retarded." Miscarriage is also possible.

This 1970 image promotes vaccination against the disease, which became available in 1969. In 1964-1965, during a major rubella outbreak, more than 20,000 children were born with disorders from the disease.

2. Diphtheria
Diphtheria, a highly-contagious bacterial disease, causes flu-like symptoms—but, left untreated, the CDC says that it "produces a toxin that can cause serious complications such as heart failure or paralysis" and kills one out of 10 of its victims.

In the 1920s, diphtheria killed approximately 15,000 victims a year, many of them children. With widespread use of the vaccine, the disease is now very rare in the U.S.. This poster dates from 1941.

3. Smallpox
The highly contagious smallpox virus causes fever, headache, vomiting, and a severe skin rash, killing many of its victims and scarring survivors. Today, smallpox cases are virtually unknown, due to a global vaccination campaign that has its roots centuries ago—the English physician Edward Jenner first vaccinated against smallpox at the end of the 18th century.

In 1809, Massachusetts became the first state to require vaccination. Vaccinations for smallpox in the U.S. continued until 1972. This image is from 1941, eight years before the last recorded case in the country.

4. Polio
The polio virus can cause symptoms ranging from those of the common cold to severe muscle pain followed by partial paralysis (often in the legs, but sometimes in other muscles). According to the CDC, a 1916 outbreak killed 6,000 people and paralyzed 27,000 others, while the National Network for Immunization Information reports that an epidemic in 1952 affected 21,000 people.

Vaccines for polio came out in 1955 and 1961; the last U.S.-originating case occurred in 1979, and the disease no longer exists in the western hemisphere. This poster is from 1963, and features "Wellbee," a CDC mascot used to promote vaccination and public health.

1. 1790
families with 11 or more members
families holding 2-4 slaves
avg. slaves per slaveholding family
free colored slaveholding families
persons of Scotch nationality
persons of Hebrew nationality

2. 1840
white persons 20 years of age and over who cannot read and write
scholars in primary and common schools
female slaves 55-99 years of age
free colored females under 10 years of age
men employed in newspaper production
persons employed in navigation of canals

3. 1870
male citizens 21 years of age and over
persons born in Africa
persons 10 and over who cannot read
total state taxation
public debt of the county
youths employed in manufacturing

4. 1880
persons born in China
Indians
colored persons
farms 500-999 acres rented for fixed money rental
average hours labor per week in iron and steel manufacturing
average youths and children employed in manufacturing

5. 1900
other colored females 5-20 years of age
illiterate foreign-born alien males 21 years of age and over
native white illiterates 10 years of age and over of native parentage
farms of colored owners and tenants
capital invested in buildings used in manufacturing
salaries of salaried officials, clerks, etc. in manufacturing

6. 1910
rural population
white persons born in asian turkey
native white males of voting age of mixed parentage
Indian, Chinese, Japanese and male of all other races of voting age
persons 15-17 years of age attending school
farms of foreign-born whites

1. A statue of Martin Luther King, Jr. stands on a pedestal engraved with these words: "His dream liberated [. . .] from itself and began a new day of love, mutual respect, and cooperation." Which city fills in the gap?

a. Birmingham, AL

The statue stands in Kelly Ingram Park in Birmingham, AL. The park, which predates the civil rights movement, was used by Martin Luther King, Jr. and the Southern Christian Leadership Conference (SCLC) as a staging point for nonviolent protests in 1963. Protesters, many of them local schoolchildren, massed here to organize for sit-ins, boycotts, and marches; in the streets around the park, law enforcement officers drenched protestors with fire hoses and menaced them with dogs. Photographs of these events created some of the most enduring images of the movement.

Today, the park contains the Freedom Walk, which leads visitors past a number of statues related to the protests, including statues of the dog attacks and children in jail.

2. A 30-foot-tall black granite pinnacle encircled by spirals of steel rises from a pool of water in front of you. You're standing in front of a memorial to Martin Luther King, Jr. in what city?

d. Seattle, WA

The Martin Luther King, Jr. Memorial Park in Seattle, WA, honors the memory of King with an abstract sculpture inspired by his final speech, "I've Been to the Mountaintop." No specific event in the civil rights movement or in King's life took place at this location; like memorials, events, and other observances nationwide, the Memorial Park sculpture, by Seattle artist Robert Kelly, reminds the surrounding community not of specific historical events but of the assumed spirit of King's life and of the civil rights movement.

3. A well-muscled African American man, wearing only a loincloth, holds his newborn up to the sky. Which city are you visiting now?

d. Atlanta, GA

Sculptor Patrick Morelli's BEHOLD stands in the Peace Plaza in Atlanta, GA. Around the plaza range sites important in the life of Martin Luther King, Jr., including his birth home and Ebenezer Baptist Church, where King preached as co-pastor with his father. Newer sites also surround the statue and plaza: The King Center, the location of King's tomb, founded by King's widow, Coretta Scott King, and the Martin Luther King, Jr. Visitor Center, maintained by the National Park Service.

4. Surrounded by trees, you walk from one upwelling of water to the next. Each small fountain, set back into a semicircular niche of stone, commemorates a martyr to the civil rights movement. You're strolling through the King memorial in which city?

c. Washington, DC

The Martin Luther King, Jr., National Memorial does not yet exist, but the memorial's design has been completed and ground broken, ceremonially, on the proposed site. When finished, the envisioned four-acre memorial will be positioned along the edge of the Tidal Basin, along a sightline stretching from the Lincoln Memorial to the Jefferson Memorial. Difficulties and controversy have dogged the memorial's progress, including backlash when Chinese sculptor Lei Yixin was chosen to carve the nearly-three-story-tall statue of King that will anchor the memorial.

1. teen (noun) [late 17th century]
the years of the life of any person of which the numbers end in -teen, i.e. from 13 to 19; chiefly in phrases in, out of one's teens.

2. teenish (adjective) [1818]
characteristic of persons in their teens, youthful.

3. teener (noun) [1894]
one in his or her teens (U.S.)

4. teen age or teen-age (adjective) [1921]
designating someone in their teens; Pertaining to, suitable for, or characteristic of a young person in his or her teens.

5. teenager (noun) [1941]
one who is in his or her teens; loosely, an adolescent.