Martin County is one of about 3,141 counties and county equivalents in the United States. It has 555.6 sq. miles in land area and a population density of 249.6 per square mile. In the last three decades of the 1900s its population grew by 352.0%. On the 2000 census form, 98.9% of the population reported only one race, with 5.3% of these reporting African-American. The population of this county is 7.5% Hispanic (of any race). The average household size is 2.23 persons compared to an average family size of 2.71 persons. In 2008 retail trade was the largest of 20 major sectors. It had an average wage per job of $25,924. Per capita income grew by 30.7% between 1997 and 2007 (adjusted for inflation).

People & Income Overview (By Place of Residence)	Value	Rank in U.S.	Industry Overview (2008) (By Place of Work)	Value	Rank in U.S.
Population (2008)	138,660	440	Covered Employment	57,339	420
Growth (%) since 1990	37.4%	484	Avg wage per job	$37,806	585
Households (2000)	55,288	373	Manufacturing - % all jobs in County	5.5%	2178
Labor Force (persons) (2008)	64,320	471	Avg wage per job	$47,219	665
Unemployment Rate (2008)	6.9	797	Transportation & Warehousing - % all jobs in County	1.9%	1706
Per Capita Personal Income (2007)	$61,868	25	Avg wage per job	$44,207	633
Median Household Income (2007)	$55,229	341	Health Care, Social Assist. - % all jobs in County	15.8%	385
Poverty Rate (2007)	8.5	2808	Avg wage per job	$42,304	352
H.S. Diploma or More - % of Adults 25+ (2000)	85.3	573	Finance and Insurance - % all jobs in County	3.2%	827
Bachelor's Deg. or More - % of Adults 25+ (2000)	26.3	328	Avg wage per job	$65,311	147