If you take the estimated annual numeric change between 2007 and 2009 and add it to the 2009 population estimate, you get a number somewhat close to what what a probable estimate would be for 2010. e.g. Between 2007 and 2009 Alabama was estimated to have added 70,804, or 35,402 per year. When you add that number to the 2009 estimate, you get 4,744,110, which is probably close to what an estimate would have been for 2010. But when you compare that number to the actual results, you find that Alabama would have been undercounted by upwards of 35,000 people.
In that sense, Florida was by far the most numerically underestimated state followed by Pennsylvania. On the flip side, Arizona and Georgia were the most numerically overestimated states. Mississippi and Minnesota had the most accurate estimates.
Here's a list:
Underestimated States
1. Florida - +133,301
2. Pennsylvania - +56,494
3. Hawaii - +55,950
4. New Jersey - +48,307
5. Maryland - +41,456
6. Connecticut - +40,982
7. Virginia - +37,014
8. Alabama - +35,626
9. New Mexico - +29,038
10. West Virginia - +28,928
11. Oklahoma - +26,869
12. Iowa - +23,931
13. Indiana - +22,189
14. North Dakota - +21,426
15. Nevada - +19,800
16. Nebraska - +16,369
17. Kansas - +12,791
18. Maine - +9,564
19. Wyoming - +8,928
20. Wisconsin - +5,611
21. Montana - +5,544
22. Alaska - +3,670
23. Vermont - +3,331
24. Arkansas - +2,840
25. Delaware - +2,699
26. Rhode Island - +258
27. Minnesota - +207
28. Mississippi - +165
Overestimated States
29. Idaho - -1,497
30. Kentucky - -3,664
31. North Carolina - -3,806
32. South Carolina - -4,383
33. District of Columbia - -4,558
34. South Dakota - -5,877
35. New Hampshire - -11,721
36. Tennessee - -11,845
37. Louisiana - -16,681
38. Ohio - -17,056
39. Missouri - -37,531
40. Washington - -39,263
41. Oregon - -40,933
42. Michigan - -45,527
43. California - -75,479
44. Utah - -81,075
45. Colorado - -86,797
46. Massachusetts - -93,114
47. Texas - -109,042
48. Illinois - -145,273
49. New York - -222,689
50. Georgia - -289,283
51. Arizona - -320,530
The Top and Bottom 10 by percentage:
1. Hawaii - +4.3%
2. North Dakota - +3.3%
3. Wyoming - +1.6%
4. West Virginia - +1.6%
5. New Mexico - +1.4%
6. Connecticut - +1.2%
7. Nebraska - +0.9%
8. Iowa - +0.8%
9. Alabama - +0.8%
10. Nevada - +0.7%
1. Arizona - -4.8%
2. Georgia - -2.9%
3. Utah - -2.8%
4. Colorado - -1.7%
5. Massachusetts - -1.4%
6. New York - -1.1%
7. Illinois - -1.1%
8. Oregon - -1.1%
9. New Hampshire - -0.9%
10. District of Columbia - -0.8%