gence of cohabitation and same-sex marriage dem-
onstrated the shifting meaning of marriage and fam-
ily in the United States. Cohabitation grew during
the 1990’s and became a more socially accepted fa-
milial alternative to traditional marriage. The num-
ber of cohabiting couples in the United States grew
from 2.8 million in 1990 to 4.5 million in 2000. The
escalation of cohabitation helped account for lower
remarriage rates.
Court decisions appeared to set the stage for legal
same-sex marriages. The Hawaii Supreme Court
ruled in 1993 that restricting marriages to opposite-
sex partners violated the equal protection clause in
the state constitution. However, in 1998, Hawaiian
voters gave the state legislature power to block same-
sex marriages, which it quickly did. The 1996 De-
fense of Marriage Act signed by President Bill
Clinton denied federal recognition to same-sex cou-
ples. However, the Vermont Supreme Court ruled in
1999 that the state must allow same-sex couples to
marry or permit them the same rights of married
couples. In April, 2000, Vermont began to recognize
civil unions.
Impact Economic and cultural changes since the
1960’s increased the prevalence of and tolerance for
diverse family forms. A weakening of social bonds
and norms that traditionally defined people’s be-
havior in the family led to negotiation of new family
roles and in new types of families. The traditional, bi-
ological two-parent family was no longer the ideal-
ized or most common family form. Birthrates
dropped, people delayed marriage, cohabitation
rates soared, and divorce rates increased.
Further Reading
Cherlin, Andrew J. “The Deinstitutionalization of
American Marriage.”Journal of Marriage and Fam-
ily66, no. 4 (2004): 848-861. Examines the chang-
ing significance of marriage in society, including
practical implications for economic well-being
and childrearing as well as symbolic meanings of
marriage in the United States.
Fields, Jason, et al.America’s Families and Living Ar-
rangements. Washington, D.C.: Government Print-
ing Office, 2001. Reports trends about house-
holds, families, and living arrangements in the
United States.
Kreider, Rose M., et al.Marital Status 2000: Census
2000 Brief. Washington, D.C.: U.S. Government
Printing Office, 2003. Presents U.S. Census data
on marital status from 1950-2000.
Martin, Teresa Castro, et al. “Recent Trends in Mari-
tal Disruption.”Demography26, no. 1 (1989): 37-- Examines the reduction in marital stability in
the United States, with emphasis on the decline
in divorce rates in the 1980’s and the leveling off
in the 1990’s.
Norton, Arthur J., et al.Marriage, Divorce, and Remar-
riage in the 1990’s. Washington, D.C.: U.S. Govern-
ment Printing Office, 1992. Includes analysis of
data from several surveys explaining patterns of
marriage, divorce, remarriage, and redivorce.
Teachman, Jay D., et al. “The Changing Demogra-
phy of America’s Families.”Journal of Marriage and
Family(2000): 1234-1246. An overview of changes
in American families related to declining preva-
lence of early marriage, increasing levels of mari-
tal dissolution, and the growing tendency to
never marry.
Barbara E. Johnson
See also Blended families; Demographics of the
United States; Defense of Marriage Act of 1996; Do-
mestic partnerships; Homosexuality and gay rights. Mars exploration
Definition The intensive study of Mars by
spacecraft
In the 1990’s, NASA began an ambitious, decade-long pro-
gram to explore Mars by flying two spacecraft to the planet
ever y twenty-six months. This program resulted in high-
quality photographic imaging of most of the surface of Mars
as well as the deployment of the first rover, a small,
semiautonomous laborator y that performed chemical anal-
ysis of rocks and soil.
Mars is the most Earth-like planet in the solar system,
so it provides insights into how Earth-like planets
evolved and, possibly, how life originated. The major
objective of the National Aeronautics and Space Ad-
ministration’s (NASA) Viking 1 and 2 spacecraft,
which landed on Mars in 1976, was to search for evi-
dence of life, possibly in the form of microorganisms
in the soil. Unfortunately, the reactive chemistry of
the Martian soil interfered with these analyses.
After a hiatus of more than fifteen years, NASA re-
sumed its exploration of Mars with the launching of554 Mars exploration The Nineties in America