| | Alton, NH | Portsmouth, NH | United States |
| Median Home Age | 42 | 63 | 42 |
| Median Home Cost | $501,600 | $644,300 | $338,100 |
| Home Appr. Last 12 months | 17.4% | 17.4% | 16.6% |
| Home Appr. Last 5 yrs. | 64.2% | 64.2% | 57.0% |
| Home Appr. Last 10 yrs. | 100.4% | 100.4% | 101.1% |
| Property Tax Rate | $17.2 | $15.0 | $11.0 |
| Homes Owned | 46.3% | 48.7% | 57.4% |
| Housing Vacant | 49.7% | 5.7% | 11.2% |
| Homes Rented | 4.0% | 45.6% | 31.4% |
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| Avg Rent For Home Or Apartment | | | |
| | Alton, NH | Portsmouth, NH | United States |
| Average Rent | $2,030 | $2,320 | $1,840 |
| Studio Apartment | $1,100 | $1,300 | $1,080 |
| 1 Bedroom Home or Apartment | $1,200 | $1,430 | $1,180 |
| 2 Bedroom Home or Apartment | $1,530 | $1,830 | $1,430 |
| 3 Bedroom Home or Apartment | $2,060 | $2,350 | $1,860 |
| 4 Bedroom Home or Apartment | $2,270 | $2,710 | $2,160 |
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| Vacant Housing | | | |
| | Alton, NH | Portsmouth, NH | United States |
| Vacant For Rent | 0.0% | 1.0% | 1.9% |
| Vacant Rented | 0.0% | 0.8% | 0.4% |
| Vacant For Sale | 0.0% | 0.6% | 0.7% |
| Vacant Sold | 0.0% | 0.0% | 0.4% |
| Vacant Vacation | 48.2% | 1.6% | 3.6% |
| Vacant Other | 1.4% | 1.7% | 4.1% |
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| Owner-Occupied Housing Value | | | |
| | Alton, NH | Portsmouth, NH | United States |
| Less Than $20,000 | 0.0% | 0.4% | 2.6% |
| $20,000 to $39,999 | 0.0% | 1.0% | 2.4% |
| $40,000 to $59,999 | 3.0% | 0.3% | 2.8% |
| $60,000 to $79,999 | 1.9% | 1.0% | 3.9% |
| $80,000 to $99,999 | 2.8% | 0.3% | 4.5% |
| $100,000 to $149,999 | 8.5% | 0.7% | 11.3% |
| $150,000 to $199,999 | 11.0% | 1.7% | 13.0% |
| $200,000 to $299,999 | 30.2% | 10.0% | 20.1% |
| $300,000 to $399,999 | 19.4% | 16.9% | 13.6% |
| $400,000 to $499,999 | 4.8% | 20.1% | 8.3% |
| $500,000 to $749,999 | 10.9% | 27.4% | 9.7% |
| $750,000 to $999,999 | 1.4% | 14.6% | 3.9% |
| $1,000,000 to $1,499,999 | 4.5% | 3.2% | 2.2% |
| $1,500,000 to $1,999,999 | 1.1% | 1.1% | 0.8% |
| $2,000,000 and over | 0.7% | 1.2% | 1.1% |
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| Housing Units By Year Built | | | |
| | Alton, NH | Portsmouth, NH | United States |
| 2015 and Newer | 0.0% | 0.0% | 0.2% |
| 2010 to 2014 | 13.2% | 6.6% | 13.6% |
| 2000 to 2009 | 13.2% | 6.6% | 13.6% |
| 1990 to 1999 | 13.8% | 5.8% | 13.6% |
| 1980 to 1989 | 13.9% | 12.8% | 13.2% |
| 1970 to 1979 | 15.9% | 8.8% | 14.8% |
| 1960 to 1969 | 13.8% | 5.8% | 13.6% |
| 1950 to 1959 | 4.9% | 11.2% | 10.0% |
| 1940 to 1949 | 1.7% | 4.6% | 4.7% |
| 1939 or Earlier | 11.4% | 36.7% | 12.2% |