table
counts | start | Stop | state
25	AL	FL	AL  
25	AL	TN	AL  
50 	AL	TX	AL  
2	AR	AR	AR   
98	AR	TX	AR  
15	CA	CA	CA  
15	CA	LA	CA  
60	CA	NJ	CA  
10	CA	TX	CA  
72	CO	TX	CO 
-------------------------------
RESULT: 
25	AL	FL	AL  25%
25	AL	TN	AL  25%
50 	AL	TX	AL  50%
2	AR	AR	AR   2%
98	AR	TX	AR  98%
15	CA	CA	CA  15%
15	CA	LA	CA  15%
60	CA	NJ	CA  60%
10	CA	TX	CA  10%
72	CO	TX	CO 100%

This returns more than 1 in subselect.. I guess a union would be more of what im looking for?

SELECT     counts, start, stops, state, (convert(decimal(10,2),counts) * 100/convert(decimal(10,2),(SELECT SUM(counts) as qty FROM dbo.BOA_stateMoves GROUP BY start))) as pct
FROM         dbo.BOA_stateMoves
Group By counts, start, stops, state
ORDER BY state, stops

--set @divideby# = select sum(counts) as StateTotal Group by [start] from table 

DECLARE @Table TABLE(counts INT, start CHAR(2), Stop CHAR(2), state CHAR(2))
INSERT @Table
SELECT 25, 'AL', 'FL', 'AL'  
UNION ALL SELECT 25, 'AL', 'TN', 'AL'  
UNION ALL SELECT 50, 'AL', 'TX', 'AL'  
UNION ALL SELECT 2, 'AR', 'AR', 'AR'   
UNION ALL SELECT 98, 'AR', 'TX', 'AR'  
UNION ALL SELECT 15, 'CA', 'CA', 'CA'  
UNION ALL SELECT 15, 'CA', 'LA', 'CA'  
UNION ALL SELECT 60, 'CA', 'NJ', 'CA'  
UNION ALL SELECT 10, 'CA', 'TX', 'CA'  
UNION ALL SELECT 72, 'CO', 'TX', 'CO' 



SELECT
	T.*,
	T.Counts * 1.00 / D.Counts
FROM
	@Table AS T
OUTER APPLY
	(
		SELECT SUM(Counts) AS Counts
		FROM @Table
		WHERE Start = T.Start
		GROUP BY Start
	) AS D

-- *** Test Data ***
DECLARE @t TABLE
(
	Counts int NOT NULL
	,Start char(2) NOT NULL
	,[Stop] char(2) NOT NULL
)
INSERT INTO @t
SELECT 25, 'AL', 'FL' UNION ALL
SELECT 25, 'AL', 'TN' UNION ALL
SELECT 50, 'AL', 'TX' UNION ALL
SELECT 2, 'AR','AR' UNION ALL
SELECT 98, 'AR', 'TX' UNION ALL
SELECT 15, 'CA', 'CA' UNION ALL
SELECT 15, 'CA', 'LA' UNION ALL
SELECT 60, 'CA', 'NJ' UNION ALL
SELECT 10, 'CA', 'TX' UNION ALL
SELECT 72, 'CO', 'TX'
-- *** Test Data ***

SELECT T.Counts, T.Start, T.[Stop]
	,CAST(T.Counts * 100.0 / D.StateTotal AS decimal(10,2)) AS StartPercent
FROM @t T
	JOIN
	(
		SELECT T1.Start
			,SUM(T1.Counts) AS StateTotal
		FROM @t T1
		GROUP BY T1.Start
	) D
		ON T.Start = D.Start
		
-- or
SELECT Counts, Start, [Stop]
	,CAST(Counts * 100.0 / StateTotal AS decimal(10,2)) AS StartPercent
FROM
(
	SELECT Counts, Start, [Stop]
		,SUM(Counts) OVER (PARTITION BY Start) AS StateTotal
	FROM @t
) D

-- or
;WITH cte (Counts, Start, [Stop], StateTotal)
AS
(
	SELECT Counts, Start, [Stop]
		,SUM(Counts) OVER (PARTITION BY Start)
	FROM @t
)
SELECT Counts, Start, [Stop]
	,CAST(Counts * 100.0 / StateTotal AS decimal(10,2)) AS StartPercent
FROM cte