Parcels

Definition

• A parcel is a piece of land or a lot (real property) identified by a unique Assessor Parcel Number (APN)

• The APN is comprised of a block number and a lot number

  • Block number format: 4 numerical digits + 1 optional letter character (0012A)

  • Lot number format: 3 numerical digits + 1 optional letter character (037B)

  • Blocks are groupings of lots which are usually contiguous and usually bounded by streets or other features on all sides

    • Blocks can be discontiguous and split by other blocks or streets

  • The City is broken up into over 6,000 blocks and over 200,000 individual lots

Note: You will see reference to mapblklot in some City data. This is to reference a 1:M relationship of vertical parcels to a base parcel; e.g. condo or timeshare lots.

The practice of representing a vertical lot digitally is to duplicate and "stack" the base parcel for each vertical lot in the building, assigning each a unique blklot number. The mapblklot is the reference to the base APN. So blklot will be unique, while mapblklot will duplicate across vertical lots.

Illustration

Image illustrating the relationship of lots to blocks

• Block 0117 above is bounded:

  • On the North and South by Union and Green Streets

  • On the East and West by Stockton and Powell Streets

• Columbus Avenue bisects it, but both sides are still part of the same block

• The block is subdivided into lots numbered from 001 through 021

• A full Assessor Parcel Number would be the concatenation of the block and lot

  • Blocks are 4 digits with an optional letter suffix - 117 becomes 0117

  • Lots are 3 digits with an optional letter suffix - 4 becomes 004

  • The full APN for lot 4 in block 117 is 0117004

• These are recorded in paper maps in the Office of the Assessor Recorder and digitized

Authority

• Recordation of final parcel maps happens with the Office of the Assessor-Recorder

• Before recordation, subdivision maps are approved by the County Surveyor, the Public Works Director and the Board of Supervisors

  • More information about the subdivision process and related codes on the Public Works website

Use

• Assessor Parcel Numbers are used to tie deeds and legal records to property

• Assessor Parcel Numbers used to assess and collect taxes on land and improvements

• As a common administrative identifier for a number of processes like permitting

Accepted values

• Must be provided in a dataset as 2 separate fields:

  • Block as blk or block or block_num - must have 4 numeric digits and an optional letter suffix

  • Lot as lot or lot_num - must have 3 numeric digits and an optional letter suffix

• When representing the fully qualified APN as a single field:

  • Name the column either apn or assessor_parcel_number or blklot or block_and_lot

  • Concatenate the block and lot values together

  • Do not separate the block and lot number with space or other characters

    • 0585012D instead of 0585/012D

  • Do not prepend with additional text like APN or Block and Lot Number

• Current parcels and corresponding identifiers in the current subdivision parcels below

• Historic parcels and corresponding identifiers in the recorded parcel geography below (note limitations)

Reference Datasets

Dataset	Description and Constraints	Block Column	Lot Column	APN Column
Current Subdivision Parcels	These are the current active recorded parcels. The geography can be used as reference but should not be used for anything requiring precision.	block_num	lot_num	blklot
Recorded Parcel Geography with Transaction Date History	These are the current and historic parcels with recorded dates. Historic parcels only go back to about 1995 with some exceptions. Useful for tying historic administrative records to a location. The geography can be used as reference but should not be used for anything requiring precision.	block_num	lot_num	blklot
San Francisco Assessor Blocks	Just the blocks without lots	block_num	N/A	N/A

Is anything wrong, unclear, missing?

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