Just keep in mind this item, from the excellent Fabius Maximus Blog,
In 1880, New York City had over 150,000 horses, a number which would rise in the next few decades. A horse produces 20+ pounds of manure and ~2 pints of urine per day. The manure flooded the market, so that farmers were paid to take it. Piles of manure were 50+ feet high. Dead and rotting horses littered the streets. All this attracted massive numbers of ﬂies which spread typhoid fever and other diseases. Horse-drawn vehicles killed people at far higher rates than today’s vehicles. The first International Urban Planning Conference convened in New York in 1898 to solve this problem. Scheduled for 10 days, they gave up on the third day and went home.