TABLE 2. Trends in suicide rates by medium and small county level of urbanization* — United States, 1999–2015.

County urbanization level	No. of counties	No. of suicides	Initial annual suicide rate increase†	p-value	Joinpoint year	Annual suicide rate increase† after joinpoint year	p-value for difference
Medium metro	331	126,447	0.14	<0.01	2008	0.41	<0.01
Small metro	339	64,739	0.19	<0.01	2008	0.41	<0.01
Micropolitan (non-metro)	694	75,002	0.19	<0.01	2007	0.45	<0.01
Non-core (non-metro)	1,355	52,075	0.18	<0.05	2007	0.55	<0.01

* Counties or county-equivalents; a small number of counties were combined into multicounty groupings. The six classification levels for counties were 1) large central metro: part of a metropolitan statistical area with ≥1 million population and covers a principal city; 2) large fringe metro: part of a metropolitan statistical area with ≥1 million population but does not cover a principal city; 3) medium metro: part of a metropolitan statistical area with ≥250,000 but <1 million population; 4) small metro: part of a metropolitan statistical area with <250,000 population; 5) micropolitan (non-metro): part of a micropolitan statistical area (has an urban cluster of ≥10,000 but <50,000 population); and 6) non-core (non-metro): not part of a metropolitan or micropolitan statistical area.

^† Per 100,000 residents aged ≥10 years, age-adjusted to the year 2000 U.S. standard.