Key takeaways

• Sanborn maps are detailed fire insurance maps made for US towns and cities.
• Insurers used them to spot fire hazards and set insurance costs.
• These maps reveal how some neighborhoods faced unfair bias.
• Today, historians and city planners study them to learn about past life.

What Are Sanborn Maps?

Sanborn maps are special fire insurance maps. From the 1860s to the 1970s, insurers used them to decide where fires might break out. They show every building, street, and landmark in great detail. For example, pink means brick and yellow means wood. This made it easy to see which blocks burned faster. Moreover, the maps label factories, stables, and brothels. In this way, they offer a window into daily life long ago.

Mapping Fire Risk

Insurers wanted to protect their money. Therefore, they studied building materials and local industries. For instance, they marked gas tanks, oil warehouses, and incinerators. If a block held many wooden homes, it got high fire risk. Also, homes near toxic factories looked more dangerous. By contrast, brick buildings meant lower risk. Thus, rates rose or dropped based on these maps. As a result, some owners paid steep fees for fire coverage.

How Sanborn Maps Showed Discrimination

Beyond fire threats, these maps reveal social bias. Insurers often thought poor or minority neighborhoods posed extra risk. For example, a Black working-class area called Lightning in Atlanta faced high rates. Its map flagged wood homes and nearby gas plants. It also noted “F.B.” for female boarding houses, a code for brothels. Although brothels did not start fires, the label meant “moral hazard.” Insurers believed that risky behavior might cost them more. Consequently, they charged higher premiums or withdrew coverage. Over time, lack of insurance led to fewer loans and little investment in such districts. This cycle deepened segregation and poverty.

Why These Maps Matter Today

Today, fire insurance maps help us study past cities in new ways. Genealogists trace family homes and trades. Historic preservationists find old building footprints. Urban planners spot former land uses that still affect us. For example, knowing where polluting industries stood can explain soil problems now. Moreover, these maps teach us how bias shaped urban growth. By comparing past maps to modern ones, we see which neighborhoods lost investment. Therefore, we can target renewal and repair old injustices.

Access and Digital Tools

Many Sanborn maps have been scanned and made public online. You can explore Library of Congress archives or state libraries. Advanced tools let you overlay old maps on today’s streets. This helps you walk virtually through a century-old neighborhood. Also, some apps let you measure building sizes and street widths from the past. As technology improves, these resources become richer and more interactive.

Lessons for City Planning

Looking back at Sanborn maps teaches vital lessons. First, planners learn how to mix industrial and residential zones safely. Back then, factories and homes shared the same blocks. Today, we know to separate them better. Second, officials see how bias in risk assessment reinforces inequality. By studying these patterns, cities can design fairer insurance policies. Finally, these maps remind us to document city changes in detail. Clear records help future experts solve tomorrow’s challenges.

From Past to Future

In the end, Sanborn maps tell a story beyond fire lines and building colors. They reveal the hopes and fears of their era. Insurers hoped to reduce payouts. City leaders hoped to protect residents, but sometimes deepened divides. Now, we hope to learn from all this. By studying these old maps, we can build cities that serve everyone fairly and safely.

Frequently asked questions

What makes Sanborn maps unique from other old maps?

Sanborn maps focus on fire risk and building details. They show materials, uses, and neighborhood features you won’t find on standard maps.

Can I view Sanborn maps for free?

Yes. Many libraries and the national archives offer free online access to scanned maps. You can search by city and year.

How accurate are the building labels on these maps?

Insurers updated them regularly. While not perfect, they offer a high level of accuracy for their time. They were drawn to protect insurance interests.

How do modern planners use these maps today?

They overlay old maps on current city maps to find hidden hazards. They also trace how land use changed over time. This guides safe development and fair housing policies.