The New York State Thruway Berkshire Spur connects the Thruway mainline to the Massachusetts Turnpike. The spur is mostly part of I-90, but the westernmost miles do not have a signed route number. This portion includes the Castleton-on-Hudson Bridge.
| Mile | Eastbound | Westbound | Notes |
|---|---|---|---|
| Albany County | |||
| Speed Limit 65 | |||
| B0.0 |  |
Exits 21B-1 SouthNew York City |
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| B0.0 | Exits 22-61 North To  Albany Buffalo |
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| Rensselaer County | Albany County | ||
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| B6.6 | Exit B1  Albany Hudson |
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| Columbia County | Rensselaer County | ||
| B15.1 | Exit B2  Taconic State Parkway Passenger cars only |
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| Virtual Ticket System Toll | |||
| B23.3 | Exit B3 Austerlitz New Lebanon |
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| Speed Limit 65 | |||
| B24.3 | Massachusetts Berkshire County |
New York Columbia County |
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