Table 1.

Characteristics of US Ambulatory Health Care Sites and Public Use Microdata Area (PUMA)

Characteristics of US Ambulatory Health Care Sites	% of Sites (N = 261,973)	% of Providers (N = 716,160)
Number of providers at site
1	49	15
2	19	13
3–5	21	27
6–10	8	20
11 or more	4	26
Site is part of multi-site group practice
No	85	73
Yes, 10 or fewer providers in group	3	3
Yes, >10 providers in group	12	25
Providers at site
Physicians only	73	50
Physicians and NPs or PAs	26	50
NPs or PAs only	1	0.3
Provider specialty mix at site
Specialist providers only	54	48
Primary care providers only	40	34
Mixed primary care and specialists	6	18
Site is owned by a hospital
No	86	76
Yes	14	24
Site is affiliated with a health system
No	88	77
Yes	12	23
Any electronic health record with e-Rx capability	30	43

Priority Population Characteristics of PUMA	PUMAs (N = 2,068)	Sites (N = 261,973)
Share of the population that is minority
Average	35	36
75th percentile	51	51
Share of the population that is low income
Average	33	32
75th percentile	41	40
Metropolitan status
Large central metropolitan	30	34
Large fringe metropolitan	24	25
Medium or small metropolitan	29	29
Non-metropolitan	17	12